The challenge
Running cold email by hand doesn't scale, and the usual tools are risky: they email people twice after a crash, keep emailing after a reply, and burn the sending domain with bad bounce handling. We needed a system that is safe by default and needs no babysitting.
What we built
- Automatic runs: checks every 10 minutes, sends inside a sending window, waits a natural 1.5 to 4 minutes between emails
- Several mailboxes sending side by side, each with its own warm-up (25, 50, 75, then 100 a day) and a bounce-rate pause
- Four-step sequences where follow-ups are replies in the original thread, from the original mailbox
- Inbox reading: replies, unsubscribes and bounces stop a lead (and their colleagues) within minutes, even mid-run
- Link-click tracking with unique links per lead, filtering out mail-security scanners
- A replies inbox to answer from the dashboard, with rich text, attachments and "send later"
- AI personalisation of first lines with Gemini, a list cleaner, CSV/Excel import and one-click backups
- Crash safety: a lead caught mid-send is held for a human check instead of being emailed twice
The result
It runs 24/7 on the same small server as this website, with no extra services. The test suite covers sending, replies, tracking, backups and edge cases, and every change ships behind those tests.