Our SES account is on probation after the bounce rate hit 5.7% in early October. That one number rewrote how we plan to send cold email from Mantis.
Short version: cold email can't go through SES anymore. The plan we're running now is boring and slow, and it's written down on purpose so nobody cheats it under deadline pressure.
Why the SES route died
Once bounces crossed 5%, the account went on probation, and cold email can't go through it now. SES is fine for transactional mail. It's not where cold outreach should live.
The inbox we're using as a reference
The closest analog to what Mantis does is a founder inbox at our sister company: about 2,200 mails, 438 of them from Bark.com. Bark sells leads for credits, so every one of those 438 mails is a lead alert to a buyer who signed up to receive it.
That is the inbound shape we care about: alerts that recipients opted into, not cold pitches blasted at strangers. It's also a reminder that "email" is really several different jobs, and each job deserves its own reputation.
The role split on mantisai.in
mantisai.in's sending reputation is currently down, so we're not pretending one mailbox can do every job. Mail is split by role:
| Mailbox | Job |
|---|---|
mantisotp@ | one-time passwords only |
mantisleads@ | Bark-style lead alerts to opted-in users |
mantisuser@ | product features, offers, lifecycle |
mantismail@ + mantismailer@ | cold outreach only |
Each role builds its own reputation. If cold tanks, OTP keeps working. If OTP has a bad week, cold doesn't get dragged down with it.
The warmup that isn't fun
Cold moves off SES to Google Workspace mailboxes: two mailboxes per domain, 20 sends per day per mailbox, and that cap only unlocks after four weeks of warmup.
Forty cold mails a day per domain, after a month of waiting, is not a growth hack. It's the floor. To scale, you add domains, not volume per mailbox.
Skipping warmup is tempting when a four-week clock sits between you and users. The plan says no, because how we landed on probation is exactly the failure warmup exists to prevent.
What we don't know yet
We don't know what reply rate looks like on the new mailboxes. We don't know how long mantisai.in's reputation will take to recover, or whether cold traffic should stay parked on a secondary domain for good. We also haven't settled on the threshold that tells us warmup is "done".
If you're on a probation list too
- Split roles before you need to: one identity for OTP, one for alerts, one for cold.
- Warm the cold mailboxes on a separate domain.
- Assume the first month earns you nothing except the right to send next month.
- Don't treat a fresh domain like a megaphone on day one.
Disclosure: I work on Mantis, a tool that helps B2B teams find customers by ICP (mantisai.in). 500 free credits once at signup, no card.
