Best Email Warmup Tools for Startups (2026)
The five email warmup tools worth comparing for Startups in 2026, with prices read off each vendor's own pricing page and an honest read on fit.
The best email warmup tools for Startups in 2026 are TrulyInbox, Mailreach, InboxAlly, Lemwarm and Warmbox. TrulyInbox publishes a free plan and then $29/mo, Warmbox starts at $15 a month yearly, Mailreach charges $19.5 per mailbox, and InboxAlly starts at $149. For startups, the deciding factor is starting the clock early enough.
Key takeaways
- Warmup is the long pole in a startup's outbound setup: the software takes minutes and the sending history takes weeks, and no plan tier shortens it.
- The five tools bill on five different units: warmup emails per day (TrulyInbox), per mailbox (Mailreach), seed emails and sender profiles (InboxAlly), per email address (Lemwarm) and a fixed inbox cap (Warmbox).
- TrulyInbox publishes a free forever plan for 1 account at 10 warmup emails/day, then $29/mo paid monthly, and connects unlimited accounts on every paid plan.
- Warmbox Solo is published at $15 /month on yearly billing for 1 inbox warm-up, and Mailreach publishes $19.5 / mailbox Per Month, so the cheaper option flips as soon as inbox count rises.
Reviewed and updated August 28, 2026
Best Email Warmup Tools for Startups (2026)
Warmup is the step that decides when a startup can actually start sending, and it is the one nobody budgets time for. The software takes ten minutes. The weeks of sending history it then has to build are the real cost, and no plan tier shortens them.
What Startups Need From an Email Warmup Tool
- Affordable pricing
- Quick setup
- Free tiers
- Room to grow without re-buying
Lead time is the requirement that matters most and gets planned least. A founder who buys domains on Monday and expects to campaign on Friday has misunderstood the category: the tool starts a process measured in weeks. The correct move is to buy the domains and start warming before the list, the copy or the sending platform are ready, so the slowest step runs in parallel with everything else.
Cost matters, and at startup scale the pricing unit barely does, because one or two inboxes cost roughly the same however they are billed. What matters is the step after that. A startup that adds inboxes as it hires will meet the difference between per-mailbox pricing and volume pricing within a year, so the question is which shape the next twelve months has rather than which is cheapest today.
Free tiers are genuinely useful here, and this list has one real one plus several trials. A free plan that warms a single inbox is enough to start the clock on the first domain while the rest of the motion is still being built.
How This Guide Was Put Together
Every price, plan name, inbox cap and volume limit here was read off the vendor's own pricing page, from a dated snapshot taken while the guide was written, and each figure is attributed to the page it came from rather than to the vendor in general. Where a figure comes from a different surface, the text says so.
No lab test sits behind this. Nobody here ran a controlled warmup across five platforms, so the guide makes no claim about which tool produces the best inbox placement. What it does judge is the pricing model, the capacity limits, and which shape of sending operation each set of published plans was drawn for.
Top 5 Email Warmup Tools for Startups
- Unlimited email accounts on every paid plan
- Priced on warmup emails per day, not inboxes
- Reply rate rising from 25% to 65% by tier
- and 5 more listed below
- Smart AI warming algorithm with dozens of parameters
- 20 spam test credits included with the warmer
- Blacklist, SPF, DKIM and DMARC monitoring
- and 5 more listed below
- Real seed-inbox engagement rather than a peer network
- 100 to 1,000 seed emails a day by tier
- 10-day free trial with no card
- and 5 more listed below
1. TrulyInbox
Warmup platform priced on the emails you send rather than the accounts you connect, with adaptive sending patterns, AI-written warmup content and per-mailbox scoring.
From the TrulyInbox pricing page: free forever for 1 account at 10 warmup emails/day, up to $479/mo paid monthly on Scale Plus, above which the plan is quoted as Custom.
| Plan (TrulyInbox pricing page) | Billed annually | Paid monthly | Warmup emails/day | Reply rate |
|---|---|---|---|---|
| Free | Free forever, 1 account | Free | 10 | |
| Starter | $22/mo, $264/year | $29/mo | 200 | up to 25% |
| Growth | $84/mo, $1,008/year | $99/mo | 1,000 | up to 45% |
| Scale | $169/mo, $2,028/year | $199/mo | 3,000 | up to 60% |
| Scale Plus | $407/mo, $4,884/year | $479/mo | 5,000 | 65% |
Two things there matter more than the prices. It states Unlimited Accounts on every paid plan, describing its model as pay for emails sent, not accounts connected, the opposite of how the rest of this list bills. And it publishes the sizing rule: warmup runs on a 2:1 ratio, two warmup emails per cold email, ongoing. That is the number to take away whichever tool you buy.
Key Features:
- Unlimited email account connections on all paid plans
- Customizable email ramp-up schedules
- AI adaptive warmup strategy
- Human-like email interaction simulation
Integrations: Gmail, Google Workspace, Outlook, Microsoft 365, Zoho Mail, SMTP, Yahoo Mail
The natural startup entry point: a free forever plan for 1 account starts the clock at no cost, and the published Starter at $22/mo annually or $29/mo monthly adds 200 warmup emails/day across unlimited accounts as inboxes multiply.
2. Mailreach
Warmup and deliverability platform that drives positive engagement signals with a multi-parameter algorithm, bundled with spam testing and DNS monitoring.
From the Mailreach pricing page: $19.5 per mailbox, per month, and above 100 mailboxes that page stops naming a number and quotes custom pricing.
| Mailreach pricing page | Published figure |
|---|---|
| Warmup rate | $19.5 / mailbox Per Month |
| Annual billing | Save 20% |
| Mailbox slider | 1, 20, 40, 60, 80, 100+ |
| Included with the warmer | 20 spam test credits |
| Sending ceiling | Up to 100 emails per day |
That page is a calculator rather than a plan ladder, so its running totals depend on where the sliders sit and no single price is what a visitor always sees. The per-mailbox rate survives every slider position, which is why it is the figure quoted here.
Key Features:
- Smart AI warming algorithm with dozens of parameters
- Automated spam testing with 20+ credits included
- MailReach Co-Pilot AI deliverability assistant
- Blacklist, SPF, DKIM, and DMARC monitoring
Integrations: Gmail, Google Workspace, Outlook, Microsoft 365, Zoho, SMTP, Mailgun, SendGrid (+1 more)
Simple and predictable at the published $19.5 per mailbox for a founder-led setup, with spam test credits included. It becomes the more expensive shape at the point the startup starts adding inboxes faster than volume.
3. InboxAlly
Deliverability platform that trains inbox placement using its own seed inboxes, which open, read and reply to your mail rather than exchanging it with other senders.
From the InboxAlly pricing page: $149 / month billed monthly, up to $1,190 / month on Premium, with Enterprise quoted as Contact us.
| Plan (InboxAlly pricing page) | Price | Seed emails per day | Sender profiles |
|---|---|---|---|
| Starter | $149 / month | 100 | 1 |
| Plus | $645 / month | 500 | 5 |
| Premium | $1,190 / month | 1,000 | 10 |
| Enterprise | Contact us | Custom volume | Unlimited |
That page publishes no annual discount, prices everything billed monthly, and offers a free trial of 10 days with no credit card required. The seed model explains the price gap: you are buying inboxes the vendor controls rather than a slot in a peer network.
Key Features:
- Real seed email engagement (opens, replies, scroll depth)
- SmartRank optimization with per-ISP reputation scoring
- Inbox simulation mimicking genuine user behavior
- Custom content control for warmup emails
Integrations: Gmail, Google Workspace, Outlook, Microsoft 365, SendGrid, Mailgun, Amazon SES, SMTP (+1 more)
At the published $149 / month it is disproportionate to an early-stage budget, and its 10-day free trial with no credit card is worth knowing about mainly as a diagnostic if a domain has already gone wrong.
4. Lemwarm
Warmup tool from lemlist that builds sender reputation across a network of real inboxes, with a technical setup check and a daily deliverability score.
From the Lemwarm pricing page: $24 per email address per month yearly or $29 monthly, up to $40 yearly or $49 monthly, above which teams of more than 10 users are quoted Custom.
| Plan (Lemwarm pricing page) | Yearly | Monthly | Priced per |
|---|---|---|---|
| Essential Plan | $24 | $29 | PER EMAIL /month |
| Smart Plan | $40 | $49 | PER EMAIL /month |
| Custom | Contact sales | Contact sales | More than 10 users |
The per-address unit is the detail to carry into a budget, because those figures read like a team price and are not. That page also offers Quarterly billing at Save 10% against Yearly at Save 20%, and states that every lemlist plan includes lemwarm, so check what you already own before buying separately. Lemwarm's homepage sizes the warm-up network at 20,000+ healthy domains in 100+ countries.
Key Features:
- Automatic email warm-up with human warm-up emails
- Warm-up network of 20k+ healthy domains
- Warm-up network tailored to your industry
- Technical setup check and deliverability reports
Integrations: Gmail, Google Workspace, Outlook, Microsoft 365, SMTP, lemlist (native), HubSpot (via lemlist), Salesforce (via lemlist) (+1 more)
At the published $24 per email address per month on yearly billing this is cheap for one or two inboxes, and if the startup already pays for lemlist that page states lemwarm is included, which makes it the cheapest option of all.
5. Warmbox
Warmup tool with fixed plans, customizable recipes, spam-score monitoring and a reporting dashboard, covering a wide spread of mailbox providers.
From the Warmbox pricing page: $15 /month on yearly billing or $19 /month monthly, up to $139 /month yearly or $159 /month monthly, above which Team plans are quoted Contact Us.
| Plan (Warmbox pricing page) | Yearly billing | Monthly billing | Inboxes | Emails/day | Members |
|---|---|---|---|---|---|
| Solo | $15 /month | $19 /month | 1 inbox warm-up | 50 emails/day | 1 |
| Start-up | $69 /month | $79 /month | 3 inbox warm-up | 250 emails/day | 3 |
| Growth | $139 /month | $159 /month | 6 inbox warm-up | 500 emails/day | 6 |
| Team | Contact Us | Contact Us | Custom | Custom | Custom |
The inbox cap decides whether Warmbox is cheap or unusable for you: Growth is the largest named plan on that page and covers 6 inboxes. A team running more than that is into Contact Us territory whatever the headline suggests, which is a very different position from the tools here that connect unlimited accounts.
Key Features:
- Automated email warm-up with AI-powered interactions
- Customizable warmup recipes and strategies
- Spam score monitoring and blacklist checks
- Real-time analytics and reporting dashboard
Integrations: Gmail, Google Workspace, Outlook, Microsoft 365, Yahoo Mail, Amazon SES, SMTP, Zoho Mail
The cheapest named paid plan on any of these pricing pages for a single inbox, published at $15 /month on yearly billing for 1 inbox warm-up at 50 emails/day. The 6-inbox ceiling on its largest named plan is the thing to check against next year's plan.
The Five Tools Price on Five Different Units
Comparing headline prices across warmup tools is close to meaningless, because no two of these five charge for the same thing.
| What you are actually billed for (from each vendor's pricing page) | Tool |
|---|---|
| Warmup emails sent per day, with unlimited accounts connected | TrulyInbox |
| Each mailbox warmed, per month | Mailreach |
| Seed emails per day and sender profiles | InboxAlly |
| Each email address, per month | Lemwarm |
| A plan with a fixed inbox cap | Warmbox |
A team with 40 inboxes sending lightly is cheapest on the tool that ignores inbox count; the same team sending hard is cheapest on the one that ignores volume. Work out both numbers before comparing any prices.
Comparison Table
| Tool (figures from its own pricing page) | Entry price | Free option |
|---|---|---|
| TrulyInbox | Free, then $29/mo monthly | Free forever, 1 account |
| Mailreach | $19.5 / mailbox Per Month | No |
| InboxAlly | $149 / month | 10-day free trial |
| Lemwarm | $24 yearly, $29 monthly | No |
| Warmbox | $15 /month yearly, $19 monthly | No |
Recommendation by Budget
Starting at nothing. The TrulyInbox pricing page publishes a free forever plan for 1 account at 10 warmup emails/day, the only ongoing free plan on this list.
The cheapest paid tiers. Warmbox Solo is published at $15 /month yearly and $19 /month monthly for 1 inbox warm-up; Lemwarm Essential Plan at $24 yearly and $29 monthly PER EMAIL /month; TrulyInbox Starter at $22/mo annually and $29/mo monthly for 200 warmup emails/day across unlimited accounts.
The middle, where the unit bites. Mailreach publishes $19.5 / mailbox Per Month, so ten mailboxes costs roughly ten times one, while TrulyInbox Growth is published at $84/mo annually and $99/mo monthly for 1,000 warmup emails/day whatever the inbox count. Those two diverge in opposite directions as a team grows.
The upper published tiers. InboxAlly starts at $149 / month for 100 seed emails per day, with $645 and $1,190 named above it, and TrulyInbox Scale is published at $169/mo annually and $199/mo monthly.
How to Choose
Start it before you are ready. Warmup is the long pole. Buy the domains and start warming while the list and the copy are still being written, because that time cannot be bought back later.
Does the next twelve months add inboxes or add volume? That answer picks between per-mailbox and volume pricing, and it is the choice a startup most often gets wrong by optimising for today.
Is there a genuinely free start? One tool here publishes a free forever plan for a single account. That is enough to begin, and it costs nothing to find out whether the workflow suits you.
Are you already paying for it? Check whether your sending platform bundles warmup before buying separately. One tool on this list is included with its parent product.
Does the daily volume match the plan? Apply the published 2:1 ratio: two warmup emails for every cold one. Most early teams need far less capacity than they buy.
Warming Without Wasting the Month
- Step 1Separate domains
Buy outbound domains that carry no client, product or transactional mail, and attach only those
- Step 2Authenticate
Fix SPF, DKIM and DMARC first, because warmup cannot compensate for a domain that fails them
- Step 3Warm at low volume
Weeks of steady sending history at the published 2:1 ratio, two warmup emails per cold email
- Step 4Send, still warming
Keep the warmup running once campaigns start, and send one message per campaign
Buy sending domains before you buy anything else, keep them well away from the domain that carries product, billing and investor mail, and start warming immediately. This is the single highest-leverage thing a founder can do in the whole setup, because it is the only step that cannot be compressed.
Ramp gradually rather than opening at full speed. New inboxes with no history get classified quickly and the damage is slow to undo.
Send one message per campaign. A startup's list is small enough that burning it with repeated sends is a real cost, and a single sharp email to fifty well-chosen people beats a sequence to five hundred badly chosen ones at this stage.
Where the Tool Stops Mattering
Warmup is necessary and nowhere near sufficient. A startup's binding constraint is almost always the list and the offer, and a perfectly warmed domain delivering a weak message to the wrong people produces a well-delivered nothing.
The second limit is patience. Outbound takes weeks to produce signal and warmup takes weeks before that, and switching tools in the middle resets the domain history along with the learning.
Final Thoughts
Start today at no cost: the TrulyInbox free forever plan. Cheapest named paid plan for one inbox: Warmbox Solo. Already paying for lemlist: lemwarm is included. Inbox count about to grow: TrulyInbox Starter. Founder-led with one or two mailboxes and no placement feedback: Mailreach.
Related Reading
- Best Lemlist Alternatives in 2026
- Best Mailreach Alternatives in 2026
- Best Warmbox Alternatives in 2026
- Best TrulyInbox Alternatives in 2026
- Best InboxAlly Alternatives in 2026
- Email sending tools for startups
If you would rather have this run for you, RevenueFlow books qualified meetings on a pay-per-meeting basis and publishes client results.
Pricing and features are taken from the vendors' own pages. Verify current terms with the vendor before relying on them.
Frequently asked questions.
Frequently asked questions- How soon should a startup start email warmup?
- Before the list, the copy or the sending platform are ready. Warmup is the only step in an outbound setup that cannot be compressed, so buying the domains and starting the warm on day one lets the slow part run in parallel with everything else. Founders who buy domains on Monday and expect to campaign on Friday have misread the category.
- Is there a free way to warm up an inbox?
- TrulyInbox publishes a free forever plan for 1 account at 10 warmup emails/day, which is enough to warm a single inbox and start the clock at no cost. Several others publish trials rather than free tiers. If you already pay for lemlist, that page states every lemlist plan includes lemwarm.
- How long does email warmup actually take?
- Longer than any signup flow suggests. The software connects a mailbox in minutes, and the sending history it then builds is measured in weeks, which is why the domains should be bought and warming before the list and the copy are ready. No plan tier shortens that, because what you are buying is time rather than throughput.
- How much warmup volume do I need?
- TrulyInbox publishes the sizing rule on its pricing page: warmup runs on a 2:1 ratio, two warmup emails for every one cold email, every day and ongoing. Multiply your intended daily cold sends per mailbox by two, add up across inboxes, and buy the plan covering that daily total rather than an average.
About the author.
B2B cold email experts helping companies generate qualified leads through done-for-you outreach campaigns.
RevenueFlow Team
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