How to warm up a new domain and IP address for email
Last updated: 26:10:2026
Why reputation starts at zero
Large mailbox providers decide where a message goes largely from how recipients have reacted to the same sender before. They track that history for the sending IP address and for the domains involved - above all the domain in the From: header and the one that signs with DKIM. A brand-new domain or IP has none of that history. It isn't "bad", it's unknown, and unknown senders that suddenly send a lot are exactly what spam looks like: spammers register fresh domains and burn through them. Spamhaus even runs a list of domains first seen in the last 24 hours, because so many of them turn out to be abusive.
Reputation is built from signals the receiver sees: messages that are opened, replied to, moved out of spam or added to contacts count for you; messages marked as spam, sent to non-existent addresses or hitting spam traps count against you. Warming up is simply giving receivers enough good signals before you ask them to accept a lot of mail.
Domain reputation vs IP reputation
- IP reputation belongs to the address mail leaves from. If you run your own server or rent a dedicated IP, you have to warm it up. On a shared IP - the usual case with hosted mail - it's shared with other customers and managed by the provider.
- Domain reputation is yours alone and follows your domain from provider to provider. Moving to a new service gives you a new IP, but your domain's history - good or bad - comes with you. A new domain has to be warmed up whatever infrastructure it uses.
Before the first message
Warm-up can't make up for missing authentication, so set this up first:
- An SPF record covering every service that will send as the domain.
- DKIM signing with your own domain, ideally a 2048-bit key.
- A DMARC record - start with
p=noneand reports, and tighten once everything passes. - Forward-confirmed reverse DNS and TLS on the sending server, if you run your own.
- A working one-click unsubscribe for anything that's a newsletter or marketing mail, and a From: address that can receive replies.
Verify all of it with the email authentication checker and a test message to a Gmail address ("Show original" should show SPF, DKIM and DMARC all passing). A domain whose first messages fail authentication starts with a bad reputation instead of none.
Ramping up volume
Google's guidance is short and worth quoting: start with a low sending volume to engaged users and slowly increase it over time, avoid sudden volume spikes if you don't have a history of large volumes, and send at a consistent rate rather than in bursts. Google also warns that suddenly doubling previously sent volumes can result in rate limiting or reputation drops.
No mailbox provider publishes a fixed schedule, and numbers you'll find online are rules of thumb rather than limits. What works is a ramp driven by results:
| Stage | Who to send to | Move on when |
|---|---|---|
| First days | Normal person-to-person mail and your most engaged contacts: people who recently signed up, bought or replied | Messages land in the inbox and there are no deferrals |
| Following weeks | Recipients who have opened or clicked in the last few months, in batches spread over the day | Bounces stay rare, complaints are near zero, no 4xx rate-limit deferrals |
| Full volume | The rest of your list - minus addresses that have been inactive for a long time | Signals stay stable at each increase; step back if they don't |
- Increase in steps, and pause on bad signals. If you see deferrals such as Gmail's
421 4.7.28("unusual rate of email") or Outlook.com's421 RP-001, go back to the last volume that worked and stay there for a few days. - Spread sends over time. A thousand messages through the day look very different from a thousand in one minute.
- Keep each kind of mail consistent. Google recommends that messages of the same category use the same From: address, and that when you change your format you increase the volume of the new format gradually too. Many senders also separate transactional and marketing mail, so a marketing problem doesn't delay password resets.
Engagement and list hygiene
Warm-up fails most often because of the list, not the volume:
- Only mail people who asked for it. Purchased, rented or scraped lists contain spam traps and addresses that bounce - the fastest route to a blocklist (see the guide to email blacklists).
- Confirm new sign-ups (double opt-in) so typos and fake addresses never enter the list.
- Remove hard bounces immediately - a
5.1.1address will never become valid (see the guide to SMTP bounce codes). - Retire inactive recipients. People who haven't opened anything for many months drag engagement down, and old abandoned addresses can be turned into spam traps.
- Make leaving easy. Every unsubscribe that doesn't happen risks becoming a spam complaint instead. Gmail and Yahoo require bulk senders to keep the user-reported spam rate below 0.3%, and Google recommends staying below 0.1%.
Monitoring the warm-up
Google Postmaster Tools
Postmaster Tools is free; you add your domain and verify it with a TXT or CNAME record in DNS. It shows whether you meet Gmail's sender requirements (the Compliance status dashboard), the user-reported spam rate, the share of mail passing SPF, DKIM and DMARC, the share sent over TLS, and delivery errors. Two caveats: data only appears once daily volume is high enough, so a domain early in its warm-up may see empty dashboards; and Google has said the old Domain and IP Reputation dashboards will be retired, so don't build your monitoring around them.
Other signals
- Bounces and deferrals from your own logs are the earliest warning. A rising share of
4.7.xreplies means slow down. - Microsoft SNDS shows per-IP data for Outlook.com - useful if you control the sending IP (see the Outlook guide).
- Inbox placement tests: send to a few seed mailboxes you own at Gmail, Outlook.com and other large providers and see where messages land.
- Blocklist checks for your domain and, if it's yours, your sending IP.
Common mistakes
- Sending a big announcement to the whole list on day one of a new domain.
- Moving all mail to a new provider or IP overnight. Move gradually where you can, starting with your most engaged recipients.
- "Warming up" with automated fake engagement - receivers recognize it, and it teaches them nothing useful.
- Pushing through deferrals by retrying harder or adding more IPs, instead of slowing down.
- Treating warm-up as a one-off: a long pause in sending and a sudden restart can need a new ramp.
How AnyMail handles warm-up
On AnyMail, mail leaves from a shared IP that we manage, with matching forward and reverse DNS, so what you warm up is your domain. Each new mail server starts with a lower hourly sending limit that rises automatically over its first two weeks, so a fresh domain can't send a sudden burst even by accident, and every message is DKIM-signed with your domain and carries one-click unsubscribe from the first send. Engagement and list quality are still up to you - for the content side, read why mail goes to spam.
Let AnyMail handle these records for you
AnyMail generates the MX, SPF, DKIM and DMARC records for your domain, checks every one of them automatically and tells you exactly which record to fix - then hosts your inboxes, operated from the EU.