A brand new IP address has no history. To a mailbox provider, a stranger that suddenly sends a million messages looks exactly like a spammer. Warm-up is how you show that you are not.
The principle
Start small, send to your most engaged recipients, and increase volume in steps while the signals stay clean. Providers see a pattern of mail that people want, and they extend trust in proportion.
A typical shape
| Phase | What you send |
|---|---|
| First days | A small volume to your most engaged recipients |
| Following weeks | Volume rises in steps |
| End | Full volume, spread through the day |
The exact numbers depend on your target volume and your audience. What matters is the direction: steady increases, never a sudden jump. After warm-up, AWS advises sending around 1,000 emails a day to each mailbox provider you want to keep a good reputation with.
Rules of thumb
- Begin with recipients who opened or clicked recently.
- Watch the bounce rate and complaint rate at every step. If either rises, hold the volume where it is until they recover.
- Spread each day’s mail over many hours.
- Keep sending every day. Gaps undo progress.
Warm-up on Amazon SES
For a dedicated IP, SES offers two routes. Standard dedicated IPs have automatic warm-up on by default, which raises a warm-up percentage over 45 days, and you can warm them by hand instead. Managed dedicated IP pools warm up automatically for each mailbox provider and scale with your volume.
Remember that your sending limits cap the ramp from above, and that an IP’s reputation is only as good as the mail you put through it while it is new.
Common questions
How long does warm-up take?
AWS says you can build a positive reputation with some providers in around two weeks, while others can take up to six weeks. SES's automatic warm-up for standard dedicated IPs raises the warm-up percentage over 45 days.
Do I need to warm up a shared IP?
No. Shared pools are already warm. A new sending domain on a shared pool still benefits from a gentle start, but there is no formal process.