Warming up a new sending domain (and when you shouldn't)
A new domain has no reputation, and no reputation reads as suspicious. How to ramp one properly — and why a fresh domain won't rescue a bad list.
A new domain doesn’t start neutral. It starts unknown, and mailbox providers treat unknown as a reason for caution — because that’s what a disposable spam domain also looks like on day one.
Warm-up is the process of building enough history that you’re no longer unknown.
Why not just send
Domain age is a signal in its own right, and a domain with no sending history that immediately starts pushing volume matches the pattern of throwaway spam infrastructure. Providers respond by deferring, filtering to spam, or rejecting.
The irony is familiar: people move to a new domain because deliverability is bad, and the move makes it worse for the first month.
A ramp that works
Roughly four weeks, climbing steadily:
| Week | Per day per address | Focus |
|---|---|---|
| 1 | 5–10 | Recipients likely to open and reply |
| 2 | 10–20 | Add real prospects, keep quality high |
| 3 | 20–30 | Normal mix |
| 4+ | ~30 | Steady state |
Two things matter more than the exact numbers:
Consistency. A domain sending 5 one day and 40 the next looks automated. An even climb looks like a business growing its outreach.
Early engagement. The first sends carry disproportionate weight. Start with recipients most likely to open and reply — warm contacts, existing customers, people expecting to hear from you. Starting a new domain on your coldest, least-verified list is the worst possible opening.
Get authentication right before the first send
Non-negotiable, and all three should be live before send one:
- SPF — which servers may send for your domain
- DKIM — a signature proving the message wasn’t altered
- DMARC — what to do when the first two fail
Start DMARC at p=none so you can watch reports without silently dropping your
own mail, then tighten once you’re confident.
When a new domain is the wrong move
If your bounce rate is the problem, a new domain will not fix it. We measured our own sending and found bounces concentrated almost entirely in scraped business addresses — 15.1%, against 1.1% to Gmail from the same domains on the same days. That’s a list problem. Move that list to a fresh domain and you’ll burn the fresh domain faster, because it has no established reputation to absorb the damage.
Verify the list first. Then, if you still want separation, warm the new domain properly with the clean list.
Also be careful with subdomains. They don’t isolate as completely as people
assume — providers roll subdomain behaviour up to the parent domain, partly
because rotating throwaway subdomains is itself a known spam pattern. A bad list
on mail.yourcompany.com can reach yourcompany.com, which is where your actual
business email lives.
The part that isn’t in the schedule
A ramp table is easy to publish and tedious to honour. It runs for a month before the domain earns anything, it has to hold its shape on the days you’re busy, and the early sends need genuinely engaged recipients — which is exactly when you’re least likely to have a clean list ready. Miss a week, or spike the volume to catch up, and you’ve taught providers the opposite of what you intended.
What to take away
- New domains start suspicious, not neutral — allow about four weeks
- Consistency and early engagement matter more than exact daily numbers
- SPF, DKIM and DMARC live before the first send
- A new domain doesn’t fix a bad list; it just gives the list a fresh victim