Free Email Warm-Up Tools, and the One With No Subscription
Most email warm-up tools only offer a free trial. We checked which ones have a real free plan, plus a free self-hosted option with no subscription.
By The Larvabot team6 min read
Most email warm-up tools sell a subscription with a short free trial, not a free plan. Of the hosted tools, only Warmup Inbox has a genuine $0-forever tier (unlimited inboxes, 15 warmup emails a week, no card needed). If you want something with no subscription at all, Mail Mantis — a free, open-source tool from the maker of Larvabot — runs the whole process yourself, on your own inboxes, for as long as you keep it running.
| Tool | Free option | Paid plans start at | Self-hosted | Best for |
|---|---|---|---|---|
| Warmup Inbox | $0 forever: unlimited inboxes, 15 warmup emails a week, no card | $15/inbox/month (billed annually) for 75 emails a day per inbox | No | A light, no-cost warm-up with zero setup |
| Warmy | 7-day free trial only, no card | $49/month | No | Teams that want a managed warm-up network |
| Mailreach | No free plan or trial found on its pricing page | About $19.50/mailbox/month | No | Agencies warming up several mailboxes at once |
| Mail Mantis | Free forever, MIT-licensed, no subscription | $0 (you run it; AI drafting may use a paid API key) | Yes (Docker or Vercel + Neon) | Founders who want full control and no recurring cost |
What does "warming up" an email domain actually mean?
Warming up means sending gradually increasing volume from a new or inactive domain so Gmail, Yahoo and other providers see it as a real sender before you ask it to carry real outreach volume. How to warm up an email domain for free covers the manual version in full: set up SPF, DKIM and DMARC, then increase daily volume slowly using inboxes you already own.
A warm-up tool automates the second part: it generates the back-and-forth mail traffic for you, so you don't have to write and send dozens of fake-but-real emails by hand every day.
Which email warm-up tools have an actual free plan, not just a trial?
Two, by our check: one hosted, one self-hosted.
Warmup Inbox's Freemium plan is $0 forever, with unlimited connected inboxes and 15 warmup emails a week, and it states no credit card is required to start. Its paid Basic tier moves you to 75 warmup emails a day per inbox, starting at $15 per inbox per month billed annually (warmupinbox.com/pricing, checked November 2026). Like other hosted tools, it works by connecting your inbox to a network it describes as 30,000-plus real accounts that exchange, open and reply to mail with you — useful for volume, but it means your warm-up mail is reaching people who have no real reason to open it.
Mail Mantis has no free plan because it has no plan at all — it's self-hosted software you run yourself, under the MIT license, with no subscription, no per-inbox fee and no seat limit (github.com/karuridavid/mailmantis). You connect inboxes you actually own (Gmail, Outlook, Yahoo, iCloud or any IMAP account), and it drafts an ordinary email for each one with AI, sends it, and checks whether the reply landed in the inbox, a tab or spam. It's manual by default, with an optional once-a-day autopilot.
Which popular warm-up tools are trial-only?
Most of the well-known names. Warmy offers a 7-day free trial with no credit card required, but its plans start at $49 a month once the trial ends, and its pricing page doesn't list a permanent free tier (warmy.io/pricing, checked November 2026). Mailreach doesn't advertise a free plan or trial on its pricing page at all; its cheapest configuration works out to roughly $19.50 per mailbox per month, with the only free item being a standalone spam-score test (mailreach.co/pricing, checked November 2026).
If you only need to warm up one or two mailboxes for a personal outreach campaign, a 7-day trial is enough to get started, but you'll be back to manual methods or a paid plan the moment it ends.
What's the catch with shared warm-up networks?
The tradeoff is simple: shared networks give you volume you couldn't generate alone, but the "engagement" comes from accounts that don't know you and have no real reason to open your mail, which is a different signal than a genuinely interested recipient opening and replying because they wanted to. Neither Google's sender guidelines nor Yahoo's sender requirements treat any warm-up method as a substitute for correct SPF, DKIM and DMARC and a spam-complaint rate under 0.3% — those are the two things both providers actually measure (support.google.com/mail/answer/81126, senders.yahooinc.com/best-practices).
That's also Mail Mantis's own disclosure about itself: it can't guarantee inbox placement, because authentication and real engagement matter more than any warm-up tool, shared network or not. If a shared network's mail gets reported as spam by any of the accounts in its pool, or filtered automatically because the pattern looks automated, that complaint counts against your domain the same way a real recipient's complaint would.
How do you choose between these?
Match the tool to how much mail you're actually about to send, and to whether you're willing to run software yourself:
- Sending to a handful of people a week, by hand: skip tools entirely and warm up manually with inboxes you own — it costs nothing but a few minutes a day.
- Running personal outreach at Larvabot's default pace (1–2 emails a day per campaign): a free hosted plan like Warmup Inbox's, or Mail Mantis if you're comfortable with Docker, covers it without a subscription.
- Sending real marketing volume across several domains or mailboxes: a paid network like Warmy or Mailreach buys you scale and support, at a recurring monthly cost.
- You want full control, your own data, and zero recurring cost, and don't mind running a container: Mail Mantis is the only option here that's both free and self-hosted.
Do you need a tool at all?
Not always. If you're sending a small volume of personal outreach rather than a marketing blast, you can warm up a domain for free with four or five inboxes you already own, by hand, in about 15–20 minutes a day for two to three weeks — the full steps are in how to warm up a new email domain. A tool mostly saves you from writing that daily back-and-forth yourself, whether that's a shared network's 30,000-plus accounts or your own handful of inboxes running on autopilot.
Larvabot sends the emails you approve through Brevo's free tier in small batches by default, 1–2 a day per campaign, which is already closer to a gentle warm-up pace than a volume blast — one more reason a brand-new domain doesn't need an aggressive warm-up network before you start personal outreach at that scale.
Frequently asked questions
Is there a completely free email warm-up tool?
Yes, in two different ways. Warmup Inbox has a genuine $0-forever hosted plan (unlimited inboxes, 15 warmup emails a week). Mail Mantis is free, open-source software you self-host, with no plan limits at all because there's no subscription.
Is a warm-up tool the same as a spam-score or placement test?
No. A warm-up tool generates ongoing sending and reply traffic to build sender history. A spam-score or inbox placement test checks a single message right now. You typically use a warm-up tool for weeks, then a placement test to confirm it worked.
How long does warming up a domain actually take?
Most senders need two to four weeks of gradually increasing volume before a new domain looks established to Gmail and Yahoo. Neither provider publishes an exact timeline, so the safest approach is to keep volume low and increase it slowly rather than aim for a fixed number of days.
Can I warm up a domain for free without any tool?
Yes. Using four or five inboxes you own, sending and replying to each other manually or with a free self-hosted tool like Mail Mantis, costs nothing but your time. The tradeoff against a paid network is volume and automation, not whether it's possible.
Do warm-up tools work with Google Workspace and Microsoft 365, not just free Gmail or Outlook accounts?
The ones in this comparison do. Warmup Inbox, Mailreach and Mail Mantis all list Google Workspace and Microsoft 365 alongside free Gmail and Outlook accounts as supported inbox types.