At a glance. IP warm-up: Ramp volume over weeks, engaged recipients first · Domain warm-up: Authenticate, then start small · Mailbox warm-up: Few real messages a day, grow slowly · Watch: Bounces, complaints, Postmaster Tools
The short version
- What warm-up is for. A mailbox provider has no history with a sender it has never seen.
- IP warm-up. A new dedicated IP has no reputation, so you ramp up volume over weeks.
- Domain warm-up. A domain has its own reputation, separate from the IP.
- Mailbox warm-up. This is the term most people mean when they search for email warm-up.
- A safe ramp. There is no universal schedule, but the shape is the same: begin with a few hundred of your most engaged recipients, double or grow by a modest step only when the last step went well, and spread the volume over the day.
- What to watch while you warm up. Watch the bounce rate, the complaint rate and where messages land.
What warm-up is for
A mailbox provider has no history with a sender it has never seen. If that sender suddenly sends a large volume, it looks like the pattern of a spammer, and the mail is filtered. Warm-up is the practice of starting small and growing, so the provider sees a pattern of wanted mail.
The idea is simple. The details differ depending on what is new: the IP address, the domain, or a single mailbox.
IP warm-up
A new dedicated IP has no reputation, so you ramp up volume over weeks. Start with your most engaged recipients, raise the daily volume in steps, and keep each step only if bounces and complaints stay low. A shared IP pool is already established, so it needs less of this.
Our warm-up calculator turns your target volume into a day-by-day plan, and our IP warmup guide explains the reasoning in more depth.
Domain warm-up
A domain has its own reputation, separate from the IP. A new domain, or a domain that has been quiet for a long time, should also start gradually, even when it sends through an established IP. Providers look at the domain in the From address and in authentication.
Set up SPF, DKIM and DMARC first, then begin with a small group of recipients who expect your mail. Do not move a large list onto a brand-new domain in one go.
Mailbox warm-up
This is the term most people mean when they search for email warm-up. It applies to a person's mailbox that sends one-to-one mail, for example in outreach. A new mailbox that sends many messages on its first day is a warning sign, so the practice is to send a few real messages a day and raise the number slowly.
Some tools automate this by exchanging messages between mailboxes. Providers do not say that such exchanges improve your reputation, and mail that nobody wanted is not the same as mail recipients engage with. That is our view, and we would not rely on it. Real, relevant mail to real people is the safer route.
A safe ramp
There is no universal schedule, but the shape is the same: begin with a few hundred of your most engaged recipients, double or grow by a modest step only when the last step went well, and spread the volume over the day.
Day 1-3: small batch, most engaged recipients
Day 4-7: grow in steps if bounces and complaints stay low
Week 2+: continue to grow toward the target volumeSend your regular mail, not a test blast. Recipients who open, click and reply give providers the signal you want, and recipients who complain or bounce tell them to be careful.
What to watch while you warm up
Watch the bounce rate, the complaint rate and where messages land. If you send to Gmail, Google Postmaster Tools shows domain and IP reputation and the spam rate. Google asks bulk senders to keep the spam complaint rate low and not to reach 0.30%.
If a step goes badly, do not push on. Go back to the last volume that worked, clean the list, and try again more slowly.
Mistakes that undo warm-up
Warming up on a purchased or old list, jumping from a small volume to a large one, mixing many kinds of mail in the first weeks, and ignoring bounces. Another is stopping: a domain or IP that sends nothing for weeks may need a gentle restart.
Before you start, validate the list and confirm that authentication passes. Our checkers take a few minutes and save weeks.
Further reading and sources
Do it in MigoSMTP: help-center articles
Related guides and tools
- IP warm-up calculator: Turn a target volume into a daily plan.
- IP warmup guide: The reasoning behind a ramp.
- Email validator: Clean the list first.
- SPF, DKIM and DMARC checker: Authenticate before you send.
Want help planning your volume? Tell us what you send and we will suggest a setup.
Frequently asked questions
What is email warm-up?
Email warm-up is sending in small, steady, increasing amounts so that mailbox providers learn to trust a new sender. The sender can be a new IP address, a new domain or a new mailbox, and the right plan depends on which.
How long does warm-up take?
There is no fixed number, because it depends on the volume you need and how recipients respond. Plans commonly ramp over several weeks. Slow down when bounces or complaints rise, and do not treat the end date as a promise.
Do email warm-up tools work?
Some tools send automated mail between mailboxes to create activity. Mailbox providers do not publish that such activity improves reputation, and it is not the same as real recipients engaging with real mail. We would rather build reputation with real, wanted mail.
Do I need to warm up a shared IP?
Usually not, because a shared pool carries mail from many senders and has an established reputation. A new domain on a shared IP still needs a gradual start, and a dedicated IP needs a proper ramp.