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MailStrike

Innovation

Agentic warmup: an AI Agent on every mailbox, writing its threads at send time

MailStrike (mailstrike.ai) is an email deliverability platform built on agentic warmup: every connected mailbox gets its own AI Agent that exchanges genuine two-way email threads with other mailboxes in the MailStrike network, with content written by an LLM at send time from the sender's industry and company description rather than from templates. It adds documented spam rescue, a placement test per mailbox per month, a daily AI deliverability summary, and standalone seed lists for B2C senders, priced per mailbox on graduated rates from $18 a mailbox a month on annual billing.

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Overview

Email warming has been through three generations, and the vendor's current positioning is an argument about the third. The first generation was fixed-volume bots trading identical messages on a schedule, which mailbox providers learned to fingerprint years ago. The second randomised timing and volume across a shared network, harder to spot but still recognisably mechanical, and still fundamentally templated. MailStrike calls its answer agentic warmup: each mailbox gets an AI Agent rather than a configuration, and the agent composes subject, body, and references in the moment from the customer's own industry and company description, so no two warming messages are alike and there is no repeated pattern for a filter to match.

An agent carries a persona made of human traits rather than a set of sliders: its own reply rate, typical dwell time on an email, active hours, and a chance of typos. The published presets are Fast Scanner, Avg Reader, Thorough Reader, and Mobile-First, changeable at any time, and the vendor recommends at least three mailboxes each running a different persona so a multi-mailbox domain looks like a team of people rather than one script repeated. Agents send only inside the sender's own working hours and timezone, never between midnight and 8am, and warming mail is labelled and archived on arrival so the real inbox stays clean.

Two things sit alongside the warming. Spam rescue is documented and logged per event: when a warming email lands in spam, a network mailbox finds it, moves it to the inbox, marks it not spam and important, and engages with it, which is the mechanism that pulls a damaged domain back. And seed lists, sold standalone and priced by volume, put monitored real consumer mailboxes onto a B2C sender's own list, either mixed into a live campaign or pre-sent before it, returning per-provider placement and rescuing the send from spam while it is still running. Coverage there is Gmail and Outlook.

The pricing model changed in September 2026 from flat mailbox bands to graduated per-mailbox rates, and the practical effect depends entirely on how many mailboxes a sender runs. Mailboxes 1 to 5 cost $18 each a month on annual billing, falling through six bands to $5 each for mailboxes 101 to 200, with each mailbox billed at the rate of the band it falls in. A single mailbox costs the same $18 it did before. Ten mailboxes come to $170 a month, fifty to $565, a hundred to $915 and two hundred to $1,415. Anything above 200 mailboxes, and seed lists, are quoted. Warming is English-only, which remains the first thing an international sender should check.

Best for

Outbound teams and agencies running fleets of mailboxes who want warming that is not templated, documented spam rescue for domains already in trouble, and a placement test on every mailbox, plus B2C senders who need seed-based placement and live spam rescue on a real campaign.

Not the right fit for

  • Programs sending primarily in languages other than English; agent threads are English-only, where Warmy documents more than 30 languages and Warmup Inbox and TrulyInbox document 12.
  • Teams that only want occasional placement diagnostics with no warming attached; a standalone tester such as Mail-Tester, GlockApps, or MailerCheck covers that narrower job for far less.
  • Buyers who want to self-serve a subscription without talking to anyone; the published route in is a booked call or the free deliverability test, and onboarding is guided.
  • Anyone expecting warming alone to fix a low-quality list or an unwanted offer; it protects reputation and placement, the content still has to earn the reply.
  • Single-mailbox senders comparing on headline price; at one mailbox this is $18 a month against $15 at Warmbox and Warmup Inbox, and the agent architecture is what the premium buys.

How it works

  1. 1

    Mailboxes connect in under two minutes each, by one-click OAuth for Google Workspace and Microsoft 365, or by app password and SMTP or IMAP for everything else. Coverage extends to Yahoo, Proton, iCloud, Zoho, Fastmail, and any provider exposing IMAP or SMTP, and because the domain is what gets warmed, campaigns sent through Amazon SES, SendGrid, Mailchimp, Brevo, or any sequencer benefit from the same work.

  2. 2

    Each mailbox is assigned an AI Agent with a persona. The agent exchanges real two-way threads with other mailboxes in the network, and those messages are opened, read, replied to, marked important, and rescued from spam, which are the engagement signals Gmail and Outlook actually weigh. Content is generated at send time in the writing style the customer picked, so the threads are multi-turn and none repeat.

  3. 3

    The customer sets the limits and the platform stays inside them: daily send volume per mailbox up to a default cap of 30 warming emails a day, raisable on request, plus ramp speed, persona, timezone, and whether warming mail is visible in the inbox. A standard ramp reaches full volume by day 21 on a clean account, with noticeable improvement around two weeks, after which warming continues indefinitely at a maintenance level of roughly 15 to 25 emails a day. Real campaigns can keep sending throughout, and warming mail never reaches a prospect.

  4. 4

    The dashboard carries a per-mailbox Inbox Reputation Score refreshed daily with a 14-day trend, a 90-day placement chart, per-provider placement, and a live feed of agent engagement including every logged spam rescue. It clears a mailbox to send once score, warmup time, and domain age all pass their thresholds, and indicates how much that mailbox can safely send. Flashman, the AI assistant, writes a daily deliverability summary per mailbox covering unusual trends, what to do about them, and outbound recommendations based on inbox health such as send volume, whether open-rate tracking is advisable, and send delays.

Feature breakdown

32 features in 5 modules

Agentic warmup

An AI Agent per mailbox rather than a set of sliders, which is the vendor's whole argument.
An AI Agent on every mailbox
Each connected mailbox gets its own agent, which mimics the owner's communication style in a writing style the customer chooses, and exchanges genuine two-way threads with other mailboxes in the network.
Personas built from human traits
An agent carries its own reply rate, typical dwell time on an email, active hours, and a chance of typos. Published presets are Fast Scanner, Avg Reader, Thorough Reader, and Mobile-First, changeable at any time.
A different persona per mailbox on a domain
On multi-mailbox domains each agent runs a distinct persona, so receivers see a team of people engaging rather than one repeated pattern. The vendor recommends at least three mailboxes, each on a different persona.
Content written at send time
Subject, body, and references are composed in the moment by an LLM from the sender's industry and company description, so threads are multi-turn and no two messages are alike. Nothing is templated, which is the specific claim against bundled warmup.
Real threads, not pings
Warming mail is opened, read, replied to, marked important, and rescued from spam by real mailboxes in the network, which are the engagement signals Gmail and Outlook weigh.
Sends only in your hours
Agents work inside the sender's own working hours and timezone and never send between midnight and 8am, so the pattern does not look automated.
Limits the customer sets
Daily send volume per mailbox up to a default cap of 30 warming emails a day, raisable on request, plus ramp speed, persona, timezone, and inbox visibility. The platform does not exceed what you set.
Warming mail hidden by default
Warming messages are labelled and archived on arrival so the real inbox stays clean, changeable in settings.
Runs alongside live campaigns
Warming continues while real outreach sends, acting as a stabiliser, and warming mail is only ever exchanged with network mailboxes, never with a prospect.

Spam rescue and recovery

The mechanism aimed at domains that are already in trouble.
Documented spam rescue, logged per event
When a warming email lands in spam, a network mailbox finds it, moves it to the inbox, marks it not spam and important, and engages with it. Every rescue is logged and visible in the dashboard's live feed.
Reputation recovery as a use case
Pulling spam-flagged, dormant, and hacked domains back to inbox placement, which the vendor puts at three to six weeks depending on the damage.
Maintenance warming that does not stop
After the 21-day ramp, warming continues indefinitely at roughly 15 to 25 emails a day per mailbox, with early-warning alerts per mailbox.
Re-warming dormant mailboxes
Sender reputation decays when a mailbox goes quiet, and the same ramp is used to bring it back before sending resumes.

Placement testing and seed lists

Two different instruments: one per mailbox on every plan, one sold separately for B2C.
One placement test per mailbox per month
Included on every plan rather than sold as credits. The email is sent and checked for inbox, promotions, or spam placement per provider, every provider covered, with results in about three minutes.
Free deliverability test
The no-cost entry point, showing placement at every major provider plus a content analysis for spam signals. Signup required, no card.
Seed lists for B2C senders
Monitored real consumer mailboxes exported in batches onto your recipient list, covering Gmail and Outlook, sold standalone and priced by seed volume with no warming plan required.
Mix-in or pre-send modes
Seeds can be mixed into a live campaign to protect a mass send, or the campaign can be pre-sent to the seeds to build content and domain signals before the real send.
Live placement plus rescue
Seeds return per-provider placement while the campaign is still running, and they open the message, rescue it from spam, dwell on it for varied periods, and a small share mark it important.
No change to your sending stack
Seeds are simply addresses on your list, exported as CSV into any sequencer, so nothing about how you send has to change.

Dashboard, analytics, and Flashman

What you look at between sends.
Inbox Reputation Score, refreshed daily
A per-mailbox score with a 14-day trend, which the dashboard uses alongside warmup time and domain age to clear a mailbox to send.
Safe-to-send guidance per mailbox
The dashboard indicates how much each mailbox can safely send, which is the number most teams otherwise guess at.
90-day placement chart
Placement over time and per provider, alongside in-depth delivery analytics.
Live activity feed
Agent engagement as it happens, including every logged spam rescue, which is the evidence that the warming is doing something.
Flashman, the AI assistant
A daily deliverability summary per mailbox covering unusual trends across your inboxes, what to do about them, and outbound recommendations based on inbox health: send volume, whether open-rate tracking is advisable, and send delays.
MCP server access
Included in the plan, so the platform can be queried and driven from an AI assistant rather than only through the dashboard.

Connection, coverage, and free tools

What it connects to, and what it gives away.
One-click OAuth for Google and Microsoft
The recommended path, with no password shared, and Google and Microsoft OAuth verification completed. Setup runs under two minutes per mailbox.
Broad provider coverage
Warms mailboxes on Google Workspace, Microsoft 365, Yahoo, Proton, iCloud, Zoho, Fastmail, and any provider exposing IMAP or SMTP.
Helps sends made elsewhere
Because the domain is what gets warmed, campaigns sent through Amazon SES, SendGrid, Mailchimp, Brevo, or any sequencer benefit without connecting those tools.
Email Auth Checker
A free tool auditing SPF, DKIM, DMARC, MX, and BIMI in one pass, with no account needed.
Blacklist Checker
Checks a domain or IP against 21 major blacklists, free and without an account.
Email Template Analyzer
Scores a cold email's subject and body separately with spam phrases weighted to SpamAssassin rule scores, validates merge tags, and previews the message on an iPhone lock screen, in the Gmail app, in the desktop Gmail inbox, and as an Outlook notification.
Record generators
Free SPF, DKIM, and DMARC record generators plus an email signature generator.

Use cases

4 documented

B2C sender with a large consumer list

An e-commerce brand is about to send a promotion to 400,000 Gmail-heavy subscribers and cannot afford a spam-folder launch day.

The team pre-sends the campaign to monitored consumer seeds at Gmail and Outlook, reads placement per provider while it is still running, fixes the variant that skewed toward spam, and relaunches with the content already carrying engagement and with seeds rescuing it from spam live.

Cold email agency managing client infrastructure

An agency runs outreach for a dozen clients across 200 mailboxes on mixed Google, Microsoft, and custom-domain setups, and needs warming, monitoring, and client-ready reporting in one place.

One account runs an agent on every mailbox with a different persona each, and the graduated rates bring the blended cost to about $9.15 a mailbox at a hundred, with a placement test per mailbox per month included rather than bought as credits.

Outbound team lead preparing a campaign launch

A sales team is about to send a new sequence to 8,000 prospects and has been burned before by campaigns that went to spam on day one.

The lead runs the actual campaign copy through a Deliverability Test from the real sending account, fixes a DKIM alignment issue the report surfaces, and launches knowing the content already landed in inboxes across providers.

RevOps recovering a damaged domain

A team's open rates collapsed after an aggressive send; their domain is on two blacklists and Gmail placement is poor.

Agents rebuild engagement gradually while documented spam rescue contradicts the filter's verdict message by message, and the daily Inbox Reputation Score with its 14-day trend shows whether recovery is actually happening. The vendor puts this at three to six weeks depending on the damage.

Pricing

from $18 per mailbox per month billed annually ($23 monthly) for the first five mailboxes

Priced per mailbox per month on graduated rates: each mailbox is billed at the rate of the band it falls in, so the blended cost per mailbox falls as the fleet grows. Rates step down at 6, 11, 16, 21, 51, and 101 mailboxes, up to 200. Above that, and seed lists, are quoted.

PlanPriceIncludes
Mailboxes 1 to 5$18
per mailbox per month billed annually, or $23 monthly
  • An AI Agent per mailbox with its own persona
  • One deliverability test per mailbox per month
  • Up to 30 warming emails a day per mailbox by default
  • Google, Microsoft, or SMTP connect
  • Dashboard, delivery analytics, and MCP server access

A single mailbox costs the same $18 it did under the old flat Solo plan, so the entry price is unchanged even though the model is not.

Mailboxes 6 to 10$16
per mailbox per month billed annually, or $20 monthly
  • Ten mailboxes total $170 a month on annual billing
  • A blended $17 per mailbox at ten
  • Everything in the band below
Mailboxes 11 to 15$14
per mailbox per month billed annually, or $17.50 monthly
  • Each mailbox billed at its own band's rate
  • Everything in the bands below
Mailboxes 16 to 20$11
per mailbox per month billed annually, or $13.75 monthly
  • Twenty mailboxes total $295 a month on annual billing
  • Everything in the bands below
Mailboxes 21 to 50$9
per mailbox per month billed annually, or $11.25 monthly
  • Fifty mailboxes total $565 a month on annual billing
  • A blended $11.30 per mailbox at fifty
Mailboxes 51 to 100$7
per mailbox per month billed annually, or $8.75 monthly
  • A hundred mailboxes total $915 a month on annual billing
  • A blended $9.15 per mailbox at a hundred
Mailboxes 101 to 200$5
per mailbox per month billed annually, or $6.25 monthly
  • Two hundred mailboxes total $1,415 a month on annual billing
  • A blended $7.08 per mailbox at two hundred
CustomQuoted
above 200 mailboxes
  • Unlimited mailboxes
  • Custom volume
  • API access

Add-ons

  • Seed Lists (Quoted by seed volume): Sold standalone with no warming plan required. Gmail and Outlook coverage, mix-in or pre-send modes, CSV export into any sequencer.

Billing notes

  • The model changed in September 2026 from flat mailbox bands to graduated per-mailbox rates, and the effect depends on fleet size. A single mailbox still costs $18. Six mailboxes, which used to be $45 on the flat Growth plan, now come to $106, and twenty, which used to be $92 on Professional, now come to $295.
  • Graduated means each mailbox is billed at the rate of its own band, not the whole fleet at the lowest rate reached. Ten mailboxes are five at $18 plus five at $16, which is $170 rather than $160.
  • Annual billing saves 20 percent against monthly across every band, and monthly plans carry no commitment.
  • One deliverability test per mailbox per month is included rather than sold as credits, which is unusual in this category and worth pricing against tools that charge per test.
  • Warming volume defaults to 30 emails a day per mailbox and can be raised on request, dropping to a maintenance level of roughly 15 to 25 a day after the 21-day ramp.
  • Seed lists are a separate quoted product and are not part of any warming plan, so a B2C sender should price them independently.
  • Prices are in USD. Above 200 mailboxes the Custom plan adds unlimited mailboxes, custom volume, and API access.

Value assessment: The September 2026 move to graduated per-mailbox rates changed who this is good value for. At one mailbox nothing moved: $18 a month, against $15 at Warmbox and Warmup Inbox and about $2 at InboxDoctor, and the agent architecture is what the premium buys. At six mailboxes the bill went from $45 to $106 and at twenty from $92 to $295, so teams that were buying a flat band and filling it have seen a real increase. Where the new model reads well is at scale, because the blended rate falls to about $9.15 a mailbox at a hundred and $7.08 at two hundred, which undercuts MailReach at $19.50 and Warmup Inbox at $15 while including a placement test per mailbox per month that both charge for. Judge it on the fleet you actually run rather than the headline: this is now among the cheapest options above fifty mailboxes and among the more expensive below ten.

Entry price history

Plans were restructured on 26 September 2026, so the current entry price is not directly comparable with the earlier one.

CheckedEntry priceWhat happened
26 September 2026$18Not comparable with the earlier figure, and a rise for most buyers. Flat mailbox bands were replaced by graduated per-mailbox rates, so the unit changed from a plan to a mailbox. One mailbox still costs $18 a month on annual billing. Six, which were $45 on the old flat Growth plan, now come to $106, and twenty, which were $92 on Professional, now come to $295. Above about fifty mailboxes the graduated rates run cheaper than the per-mailbox field, reaching $5 a mailbox from 101 to 200.
20 September 2026$18/mo billed annually (one mailbox)First recorded

Dates are when SaaSTracker checked the vendor’s published pricing, not when the vendor changed it. See the price changes log for movements across the whole database.

Strengths & limitations

Strengths

  • An AI Agent per mailbox composes its threads at send time from the company description, so there is no template for a filter to fingerprint, which is the property shared-network and configured-pattern tools cannot replicate.
  • Seed lists are sold standalone and need no warming plan, which lets a B2C sender buy per-provider placement and live spam rescue on a real campaign without subscribing to the warming product at all.
  • Placement tests send from the user's own connected account through the real campaign path, with no seed lists to copy and no codes to paste.
  • Spam rescue is documented and logged per event, so a customer can see each time a warming email was pulled out of spam rather than take the outcome on trust.
  • Flat tiers with placement tests and monitoring bundled bring a full 20-mailbox Professional plan under $5 per mailbox per month.
  • Agency tooling (client grouping, exportable reporting, and API access with webhooks on Custom plans) is unusually complete for the price point.

Limitations

  • Agent threads are English-only, so programs sending mainly in other languages should look at Warmy, which documents more than 30 languages, or Warmup Inbox and TrulyInbox at 12.
  • No free plan and no advertised free trial; every tier on the pricing page starts from a booked call, with a free deliverability assessment as the evaluation path.
  • Deliverability tests are metered per tier (a single test a month on Solo), pricing above 20 mailboxes is quoted, and the Seed Lists add-on is priced per customer rather than self-serve.
  • Deliverability-focused by design: MailStrike sends no campaigns, so it always runs alongside a sending platform rather than replacing one.

Head-to-head comparisons

18 alternatives

MailStrike vs MailReach

from $19.50 per mailbox per month, or $16 per mailbox per month billed annually

MailReach is the category's established name with a well-regarded warming network and spam checker; MailStrike is the generational bet, with an AI Agent behind every mailbox writing its threads at send time, and seed lists built for pre-sending whole campaigns rather than spot-checking them. Teams that value track record pick MailReach; teams that want the newest warming architecture and pre-launch priming pick MailStrike.

Full MailStrike vs MailReach comparison

MailStrike vs Warmy

from Not published; volume-based quote after a 7-day trial

Both are all-in-one deliverability consoles with warming, DNS tooling, and placement checks. Warmy is broader on ESP integrations; MailStrike counters with agentic warmup, graduated rates that reach about $7 a mailbox at two hundred, and standalone seed lists for campaign pre-sends. Mixed-ESP marketing senders lean Warmy; agencies and B2C senders scaling mailboxes and launches lean MailStrike.

Full MailStrike vs Warmy comparison

MailStrike vs InboxAlly

from $149/month

InboxAlly proved the engagement-priming model, human-operated seed inboxes that rescue and engage mail, and remains a strong focused instrument. MailStrike extends the same principle with an AI Agent per mailbox on the warming side and standalone seed lists on the pre-send side, wrapped in a fuller console with a daily reputation score and a placement test per mailbox. Single-job buyers keep InboxAlly; teams that want priming plus the full loop step up to MailStrike.

Full MailStrike vs InboxAlly comparison

MailStrike vs GlockApps

from $59/mo (Essential, billed annually)

GlockApps is the deeper pure diagnostic: wide seed coverage, DMARC analytics, consultant-grade reports, and no warming attached. MailStrike measures from the user's own account and folds results into the platform that also warms and primes. Audit-grade measurement favors GlockApps; operators who want to test, fix, and prime in one product favor MailStrike.

Full MailStrike vs GlockApps comparison

MailStrike vs Instantly

from $47 per month, or $37.60 per month billed annually (Outreach Growth)

Instantly bundles warming into the sending platform: configurable open and reply rates against a shared pool of platform accounts, with the better-aged tiers paid and placement tests gated above two free ones. MailStrike sends no campaigns at all, so it runs alongside Instantly at the mailbox level rather than replacing it, warming with a distinct AI Agent per mailbox instead of a configured pattern. Teams wanting one bill for sending and warming stay with Instantly; teams that want the warming layer independent of the sequencer add MailStrike underneath it.

Full MailStrike vs Instantly comparison

MailStrike vs Smartlead

from $39 per month, or $32.50 per month billed annually (Base)

Smartlead includes unlimited warming on every plan against a pool it describes as private and vetted, configured per mailbox for volume, ramp, and reply rate, with spintax content and an identifier tag in each warmup email. MailStrike writes threads at send time from the company description with nothing tagged or templated, and bundles placement tests into every tier rather than selling them as an add-on. Agencies wanting sending and warming on one invoice pick Smartlead; those who want warming that leaves no fingerprint run MailStrike beside it.

Full MailStrike vs Smartlead comparison

MailStrike vs lemlist

from $69 per month, or $55 per month billed yearly (Email)

Lemwarm ships free inside every lemlist plan and warms through a shared pool with industry clusters, which is difficult to argue with on price. Its published material documents no automated spam rescue, and the mark-as-important step is a filter rule the customer sets on their own inbox. MailStrike charges separately but automates both, logs rescue per event, and includes placement tests on every tier. lemlist users content with bundled warming stay put; those who need warming they can evidence pay for MailStrike.

Full MailStrike vs lemlist comparison

MailStrike vs Warmup Inbox

from $15/inbox/mo (Basic, billed annually at $180/yr)

Warmup Inbox is the stronger pick on reach: warming in twelve languages to MailStrike's English only, plus outreach sequences bundled into paid plans and blacklist monitoring across more than a hundred lists. MailStrike differentiates on behaviour, giving each mailbox its own agent with a distinct reply rate, dwell time, active hours, and typo chance rather than one warming pattern per inbox, and writing content at send time from the company's own description. Multilingual programs should pick Warmup Inbox; English-language senders who want per-mailbox distinctiveness pick MailStrike.

Full MailStrike vs Warmup Inbox comparison

MailStrike vs Warmbox

from $15/mo (Solo, billed annually)

Warmbox is the no-frills option: a private network of aged inboxes, templated content, adjustable reply rate and working-hours scheduling, and a free DNS and blacklist checker at a low solo price. Its material documents no placement test, no seed lists, and no AI assistant. MailStrike costs more and adds all three, plus an AI Agent per mailbox and a daily reputation score. Solo senders who only need warming traffic pick Warmbox; teams that have to prove where mail landed pick MailStrike.

Full MailStrike vs Warmbox comparison

MailStrike vs TrulyInbox

from $0 (Free), then $22 per month billed annually (Starter, $29 monthly)

TrulyInbox prices by daily volume with unlimited mailboxes on every paid plan, warms in twelve languages, offers a genuine free plan, and supplies Saleshandy's warmup as a third-party partner. It documents no placement test and no seed lists. MailStrike is English-only with no free plan, but includes placement tests in every tier and sells Seed Lists standalone for campaign pre-sends. Volume-priced multilingual warming favors TrulyInbox; measurement and pre-send priming favor MailStrike.

Full MailStrike vs TrulyInbox comparison

MailStrike vs Mailivery

from $21.75/mo (Starter, billed annually; $29 monthly)

Mailivery bundles unlimited mailboxes, verification credits, blacklist monitoring, and occasional placement tests into one flat subscription against a shared warm-up pool. MailStrike gives each mailbox its own agent rather than pooling behaviour, scores reputation daily with a 14-day trend, and includes a placement test per mailbox per month, but ships no verification of its own. Teams wanting warming and list hygiene on a single bill pick Mailivery; teams who want the warming itself to be per-mailbox distinct pick MailStrike.

Full MailStrike vs Mailivery comparison

MailStrike vs InboxDoctor

from $2 per mailbox per month (B2B Starter)

InboxDoctor sets the price floor of the category at roughly two dollars a mailbox, with placement tests bought as credits rather than bundled. MailStrike costs several times that at small fleets, though the gap narrows to about $5 a mailbox above a hundred, and answers with a distinct AI Agent per mailbox and a placement test included per mailbox per month. Agencies warming hundreds of mailboxes on thin margins pick InboxDoctor; teams whose sending reputation carries real revenue pick MailStrike.

Full MailStrike vs InboxDoctor comparison

MailStrike vs Folderly

from $96 per mailbox per month billed annually (Folderly), or $0 (Inbox Insights and Pulse free tiers)

Folderly is the enterprise end of the category, a full deliverability operation with auditing, monitoring, and hands-on remediation at around $96 a mailbox. MailStrike delivers warming, placement testing, and DNS guidance at a fraction of that price, with an agent per mailbox and graduated rates that fall to $5 above a hundred mailboxes, but without Folderly's depth of managed service and human oversight. Teams buying deliverability as a managed operation pick Folderly; teams running it themselves pick MailStrike.

Full MailStrike vs Folderly comparison

MailStrike vs Allegrow

from $99/mo (Starter, 5,000 verifications)

Allegrow works inside the sequencer, blocking risky sends before they go and tracking spam rates per rep, and now leads with enterprise-grade verification at a $99 entry point. MailStrike sits outside the sequencer entirely, building each mailbox's reputation before campaigns run and testing placement from the user's own account. Funded B2B teams who want guardrails enforced mid-sequence pick Allegrow; teams who want the underlying mailbox reputation built and measured pick MailStrike.

Full MailStrike vs Allegrow comparison

MailStrike vs MailGenius

from $0 (free spam test), then $23 per month (Beginner)

MailGenius is a diagnostic rather than a warmer: a free spam test that grew into automatic pre-send checks and blacklist alerting, with plain-language reasons for every finding. MailStrike diagnoses too, but exists to build the reputation in the first place, through an AI Agent per mailbox and seed list pre-sends. Senders who only need to know why a message trips filters pick MailGenius; senders who need the mailbox itself trusted pick MailStrike.

Full MailStrike vs MailGenius comparison

MailStrike vs Unspam

from $0 (Free, 21 tests a month), then pay per test on Custom

Unspam is the cheapest way to score a message, check placement per provider, and preview rendering across clients, all from one credit pool with a free tier. It does no warming at all. MailStrike previews no rendering and costs considerably more, but warms the mailbox and includes placement tests on every tier. Teams checking what they send pick Unspam; teams fixing how they send pick MailStrike, and the two sit comfortably side by side.

Full MailStrike vs Unspam comparison

MailStrike vs MailerCheck

from $10 (1,000 credits, pay as you go)

MailerCheck comes at deliverability from the data side: cent-per-check verification from the MailerLite family, with placement and content testing bolted on and no warming at all. MailStrike comes at it from the sending side, warming each mailbox and folding testing into the loop, with no verification of its own. They complement rather than compete, and outbound teams at volume generally end up paying for both.

Full MailStrike vs MailerCheck comparison

MailStrike vs Mail-Tester

from $0 (3 tests per 24 hours), then $10 per month for 50 tests

Complementary layers rather than alternatives. Mail-Tester scores a single message against SpamAssassin, free three times a day, and reports what in the content, the HTML, the links, or the authentication cost points. MailStrike warms the mailboxes that will send it, scores reputation daily, and includes a placement test per mailbox per month from the sending account itself. Neither replaces the other: use the free score while the copy is still being edited, and a warming and monitoring platform behind the mailboxes for everything that happens after send.

Full MailStrike vs Mail-Tester comparison

Pairs well with

Reviewed September 2026

MailStrike is a deliverability tool, and a team running it still has 8 neighbouring categories to staff. The pick in each is Instantly for cold email outreach, InboxKit for cold email infrastructure, ZeroBounce for email verification, Mailchimp for email service providers, Reply.io for sales engagement, AiSDR for AI SDR agents, HubSpot CRM for sales CRM and Google Analytics 4 for GTM analytics, each the leading tool in that category on published criteria.

  1. InstantlyCold Email Outreach · Category Leader
    Because
    MailStrike sends no campaigns, so a sequencer is not optional beside it. Instantly runs the mailboxes and the sequences MailStrike is measuring and warming.
    Benefit
    Outreach goes out on a schedule and replies land in one place instead of a personal inbox.
  2. InboxKitCold Email Infrastructure · Category Leader
    Because
    MailStrike protects sender reputation but provisions no mailboxes or domains. InboxKit registers the domains, creates the inboxes, and hands over the sending estate MailStrike then monitors.
    Benefit
    Sending moves off the main domain, so a burned domain costs a spare rather than the company's email.
  3. ZeroBounceEmail Verification · Category Leader
    Because
    MailStrike's own profile says warming cannot fix a low-quality list. ZeroBounce removes the dead addresses before the bounce rate reaches the reputation MailStrike is protecting.
    Benefit
    Dead addresses come off the list before the send, so the bounce rate never touches the domain.
  4. MailchimpEmail Service Providers · Category Leader
    Because
    MailStrike watches reputation on outbound mailboxes and stores no audience. Mailchimp holds the opt-in list and sends to it, on the sender reputation MailStrike exists to protect.
    Benefit
    An opt-in audience is owned rather than rented, and reaching it costs nothing per send.
  5. Reply.ioSales Engagement · Category Leader
    Because
    MailStrike covers one channel's deliverability and no sequencing at all. Reply.io runs the multichannel cadence, with calls and LinkedIn steps beside the email MailStrike keeps landing.
    Benefit
    One cadence covers email, calls and LinkedIn, so nobody drops a follow-up between tools.
  6. AiSDRAI SDR Agents · Category Leader
    Because
    MailStrike writes no emails and books no meetings. AiSDR does both, from mailboxes MailStrike keeps warm and monitored so the agent's volume does not sink them.
    Benefit
    Research, writing and sending happen without a headcount, and the meetings still get booked.
  7. HubSpot CRMSales CRM · Category Leader
    Because
    MailStrike holds no contacts, deals or pipeline, only mailbox health. HubSpot CRM is where the replies MailStrike's work earns become records someone can act on.
    Benefit
    Every conversation ends up on a record, so a rep leaving does not take the pipeline with them.
  8. Google Analytics 4GTM Analytics · Category Leader
    Because
    MailStrike reports inbox placement and reputation, never revenue. Google Analytics 4 is where a landed email becomes a session, a conversion, and a number a founder cares about.
    Benefit
    Spend gets attributed to revenue, so the channel that works is the one that gets funded.

Pairings follow the methodology: the leading tool in each complementary category, chosen on published criteria. Placement cannot be purchased.

Full MailStrike stack

Implementation & onboarding

Setup time
Under two minutes per mailbox: one-click OAuth for Google Workspace and Microsoft 365, or an app password over SMTP and IMAP for Yahoo, Proton, iCloud, Zoho, Fastmail, and anything else. Onboarding is guided by the team. A fresh domain still needs the 21-day ramp before meaningful volume, with noticeable improvement around two weeks; seed list onboarding is arranged separately when that product is quoted.
Learning curve
Low. Persona warming and monitoring are automatic after connection; the placement tester is a single form. DNS fix guides assume no prior deliverability knowledge.
Onboarding
Every published tier starts from a booked onboarding call; Custom plans add a dedicated account manager, priority support, and an SLA.
Migration notes
Switching from another warming tool is low-friction since no campaign data lives in the tool; disconnect there, connect here, and expect a short re-ramp while Personas establish their engagement patterns.

Platform, API & security

Platforms
Web appMCP serverREST API (Custom plans)
API
An MCP server is included in the plan, so the platform can be queried and driven from an AI assistant rather than only through the dashboard. A REST API for mailbox management and analytics arrives on Custom plans above 200 mailboxes.
Compliance
CASA Tier 2 (assessed and validated by TAC Security)Google OAuth verifiedMicrosoft OAuth verifiedGDPR-aligned processes
Data residency
Not published; the company is based in Poland.
Security notes
Mailbox connections use one-click OAuth for Google and Microsoft with no password shared, and app password or SMTP and IMAP credentials for everything else. The CASA Tier 2 assessment, validated by TAC Security, is the strongest published security posture among the standalone warming tools in this category, several of which publish none at all.

Support & resources

Channels
Email support (all tiers)Priority email and chat (Growth+)Dedicated account manager (Agency)
Documentation
Product documentation plus API docs with a live playground for Agency-tier developers; DNS and delisting guides are written per provider in plain language.

Company

Founded
2026
Headquarters
Poland
Ownership
Backed by IT Monks
Employees
Not disclosed
Funding
No funding amount disclosed. The company states it is backed by IT Monks.

Timeline

  1. 2026Founded in Poland with backing from IT Monks, and launched as an agentic warmup engine: an AI Agent per mailbox, real two-way threads across its own network, and documented spam rescue.
  2. 2026Ships the in-app deliverability test, placement checked per provider from the user's own connected account with results in about three minutes, included one per mailbox per month.
  3. 2026Adds Flashman, an AI assistant writing a daily deliverability summary per mailbox, and standalone Seed Lists for B2C senders covering Gmail and Outlook.
  4. 2026Completes a CASA Tier 2 security assessment validated by TAC Security, alongside Google and Microsoft OAuth verification.
  5. 2026Moves pricing in September from flat mailbox bands to graduated per-mailbox rates from $18 down to $5, and repositions the warming engine publicly as agentic warmup with persona presets per agent.

Integrations

  • Google Workspace, by one-click OAuth
  • Microsoft 365, by one-click OAuth
  • Yahoo, Proton, iCloud, Zoho, and Fastmail
  • Any provider exposing IMAP or SMTP, by app password
  • Runs alongside sequencers and senders such as Apollo, Instantly, Smartlead, Amazon SES, SendGrid, Mailchimp, and Brevo
  • MCP server, for querying and driving the platform from an AI assistant
  • CSV export of seed lists into any sequencer

Frequently asked questions

15 questions

What is MailStrike?

MailStrike is an email deliverability platform built on agentic warmup. Every connected mailbox gets its own AI Agent, which exchanges genuine two-way threads with other mailboxes in the MailStrike network, with subject, body, and references written by an LLM at send time from the sender's industry and company description rather than from a template. Around that sit documented spam rescue, a placement test per mailbox per month, a daily AI deliverability summary, and standalone seed lists for B2C senders.

What is agentic warmup, and how is it different from ordinary warming?

Ordinary warming is configuration: you set an open rate, a reply rate, a daily volume, and a template pool, and the platform reproduces that pattern. Agentic warmup gives each mailbox an agent with a persona made of human traits, its own reply rate, typical dwell time, active hours, and even a chance of typos, and has it compose each message in the moment. The vendor's argument is that a templated pattern is exactly what Google and Microsoft now detect, and the counter-argument a buyer should weigh is that this is harder to verify from outside than a published open rate.

How much does MailStrike cost?

It is priced per mailbox per month on graduated rates, so each mailbox is billed at the rate of the band it falls in. Billed annually, mailboxes 1 to 5 are $18 each, 6 to 10 are $16, 11 to 15 are $14, 16 to 20 are $11, 21 to 50 are $9, 51 to 100 are $7, and 101 to 200 are $5. Monthly billing runs $23, $20, $17.50, $13.75, $11.25, $8.75, and $6.25. That puts ten mailboxes at $170 a month, fifty at $565, a hundred at $915, and two hundred at $1,415 on annual billing. Above 200 mailboxes is quoted, and seed lists are priced separately by volume.

Did the price go up?

For most buyers, yes. The model changed in September 2026 from flat bands to graduated per-mailbox rates. A single mailbox still costs $18 a month. But six mailboxes, which used to be $45 on the flat Growth plan, now come to $106, and twenty, which used to be $92, now come to $295. Above roughly fifty mailboxes the new model is competitive with the per-mailbox field and cheaper than MailReach or Warmup Inbox, so whether this was a rise or a fall depends entirely on the size of the fleet.

What does a persona actually control?

An agent's reply rate, typical dwell time on an email, active hours, writing style, and chance of typos. The published presets are Fast Scanner, Avg Reader, Thorough Reader, and Mobile-First, and a mailbox's persona can be changed at any time. On a domain with several mailboxes each agent runs a different persona, so receivers see a team of people rather than one repeated pattern, and the vendor recommends at least three mailboxes set up that way.

What are MailStrike's seed lists?

Monitored real consumer mailboxes, covering Gmail and Outlook, exported in batches onto a B2C sender's own recipient list. They can be mixed into a live campaign to protect a mass send, or the campaign can be pre-sent to them first to build content and domain signals. They return per-provider placement while the campaign is running, and the seeds open the message, rescue it from spam, dwell on it for varied periods, and a small share mark it important. They are sold standalone, priced by seed volume, and need no warming plan.

Is there a free trial?

No trial is published. The no-cost entry point is the free deliverability test, which shows placement at every major provider plus a content analysis for spam signals, and needs a signup but no card. Otherwise the published route in is a booked call with a mailbox connected on the spot, after which onboarding is guided.

How long does warming take?

A standard ramp reaches full volume by day 21 on a clean account, with noticeable improvement around two weeks. Bounce spikes, spam complaints, and sudden volume jumps slow the curve. After the ramp, warming continues indefinitely at a maintenance level of roughly 15 to 25 emails a day per mailbox rather than stopping.

Which email providers does MailStrike support?

Google Workspace and Microsoft 365 connect by one-click OAuth, and Yahoo, Proton, iCloud, Zoho, Fastmail, and anything else exposing IMAP or SMTP connect by app password. Setup runs under two minutes per mailbox. Because the domain is what gets warmed, campaigns sent through Amazon SES, SendGrid, Mailchimp, Brevo, or any sequencer benefit without being connected.

Does MailStrike support languages other than English?

No. Agent threads are English-only. Warmy documents warming in more than 30 languages and Warmup Inbox and TrulyInbox in 12, so a programme sending mainly in another language should look there first. Placement testing and the free tools are language-independent.

Can MailStrike fix a domain that is already in spam?

Recovery is one of its core use cases, and the mechanism is documented spam rescue: when a warming email lands in spam, a network mailbox finds it, moves it to the inbox, marks it not spam and important, and engages with it, with every rescue logged per event in the dashboard's live feed. That directly contradicts the filter's verdict, which is what pulls a damaged domain back. The vendor puts recovery at three to six weeks depending on the damage.

Does MailStrike replace Instantly or Smartlead?

No. MailStrike sends no campaigns and is not a sequencer, CRM, or lead database. It connects to the mailbox rather than to the sending tool, so campaigns never pause and warming mail is labelled and archived on arrival, never reaching a prospect. Teams on platforms with bundled warm-up add it underneath for warming that is not templated, and switch the bundled warm-up off.

What should I pair MailStrike with?

MailStrike is a deliverability tool, and a team running it still has 8 neighbouring categories to staff. The pick in each is Instantly for cold email outreach, InboxKit for cold email infrastructure, ZeroBounce for email verification, Mailchimp for email service providers, Reply.io for sales engagement, AiSDR for AI SDR agents, HubSpot CRM for sales CRM and Google Analytics 4 for GTM analytics, each the leading tool in that category on published criteria.

What do I pair with MailStrike for Cold Email Outreach?

Instantly. MailStrike sends no campaigns, so a sequencer is not optional beside it. Instantly runs the mailboxes and the sequences MailStrike is measuring and warming.

Is MailStrike enough on its own?

For deliverability, yes. MailStrike does not cover cold email infrastructure, email verification and email service providers, and its own profile says so; InboxKit, ZeroBounce and Mailchimp are the tools that fill those gaps.

Editorial verdict

MailStrike's argument is that templated warming has stopped working, and its answer is to give every mailbox an agent rather than a configuration: a persona with its own reply rate, dwell time, active hours and typo chance, composing each thread at send time from the sender's own company description so there is no pattern to fingerprint. Whether that beats a well-configured shared network is not something a buyer can verify from outside, and the honest framing is that it is the most specific architectural claim in the category rather than a proven one. What is verifiable is the surrounding kit, and it is strong: documented spam rescue logged per event, a placement test included per mailbox per month where most rivals sell tests as credits, a daily reputation score with a 14-day trend, an AI assistant writing a daily summary per mailbox, broad provider coverage, and standalone seed lists for B2C senders. The September 2026 repricing is the thing to model before buying. A single mailbox still costs $18, but six went from $45 to $106 and twenty from $92 to $295, while the graduated rates make large fleets genuinely cheap at about $9.15 a mailbox at a hundred and $7.08 at two hundred. Below ten mailboxes this is now one of the more expensive options in the category; above fifty it is one of the cheapest. English-only warming remains the hard limit, and there is no trial, so the free deliverability test and a booked call are the way in.

Written by the SaaSTracker editorial team. Awards, when shown, are judged against the published criteria in our methodology.

Awards & badges

1 held

MailStrike holds 1 award from the SaaSTracker editorial program. Badges may be displayed by the vendor; each embed links back to this profile.

SAASTRACKER SUMMER 2026 Innovation

Innovation · Email Deliverability & Warming

“Rethought warming twice in one product: an AI Persona behind every mailbox in place of detectable network patterns, and a seedlist of thousands of trusted inboxes that campaigns are pre-sent to at scale for delivery feedback and engagement before launch.”

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