Warming up
Transactional email API
Warmbox is a warmup-only tool with a private warming network and a focus on inbox placement visibility. It supports Gmail, Outlook, and SMTP — but prices per inbox, which adds up fast once you scale beyond a handful of mailboxes.
The cheaper, specialised alternative. Warmup-only, warmup included on every mailbox, daily auth checks, 5-provider placement insight.
Dedicated warmup with a private peer network, priced per inbox.
| Warmerly | Warmbox | |
|---|---|---|
| Pricing model | Flat, mailboxes and warmup included | Per inbox |
| Starting price (per month) | $19 | ~$19–29 / inbox |
| 5 mailboxes monthly cost | $19 | ~$95–145 |
| 10 mailboxes monthly cost | $19 | ~$190–290 |
| Spam-folder rescue | Every 10 minutes | Available (check plan) |
| Reply with quoted history | Yes | Yes |
| Inbox placement seeds | Same- and cross-provider | Yes (check current coverage) |
| Auth monitoring (SPF/DKIM/DMARC) | Daily, with remediation copy | Status indicator |
| Reputation drop alerts | Email + webhook + Slack | |
| SMTP mailbox support | Gmail, Microsoft 365, any IMAP/SMTP | Gmail, Outlook, SMTP |
| API access | Agency plan | Check current docs |
| USD/GBP billing & EU data residency | Yes | No |
| Free plan / trial | Free plan (no card), or a 7-day trial | Trial available (check warmbox.io) |
| Try before you pay | Free plan (no card) + 7-day trial; no refunds after the first charge | Check their terms |
Warmbox is a capable warmup tool with solid fundamentals. If you need to warm SMTP mailboxes (non-Google, non-Microsoft), it is one of the few tools that supports that. For Gmail and Outlook users managing more than 2 or 3 mailboxes, Warmerly's flat rate is dramatically cheaper — and the daily auth monitoring adds meaningful protection that per-inbox tools rarely prioritise.
Yes. Both warm Gmail, Microsoft 365 and generic IMAP/SMTP mailboxes with active warmup sequences: peer replies, spam recovery, and positive engagement signals.
Warmerly is flat-rate — $19 for 5 mailboxes, $49 for 25 — so the price per mailbox falls as you add them. Warmbox charges per inbox, so its bill climbs with every one. At 10 mailboxes, Warmerly's $49 Growth plan sits against a Warmbox bill several times larger. Always verify Warmbox's current pricing at warmbox.io before comparing.
No. Mailbox reputation is held by Gmail and Microsoft, not by your warmup tool. Switching tools does not affect it. Warmerly will pick up where Warmbox left off. Connect your mailbox, choose a ramp schedule, and the warmup continues seamlessly.
About 2 minutes per mailbox. Disconnect from Warmbox, connect to Warmerly via the Google or Microsoft OAuth flow, select a ramp curve, and you are live. No DNS changes required.
Connect a mailbox to Warmerly in 60 seconds. Free plan, no card required. Paid plans start with a 7-day trial, first charge on day 8, cancel any time before then. We will warm right alongside whatever you use now, so you can A/B without commitment.