Warming Tiers
New domains start with rate limits that lift as the shared IP learns your sending pattern.
Why warming exists
Atmosphere Mail members share an IP pool. A new domain that immediately sends thousands of messages could damage the pool's reputation for everyone. Warming tiers cap outbound volume for new members so mailbox providers (Gmail, Outlook, Yahoo) can build a positive association with your domain gradually.
The three tiers
| Tier | Duration | Hourly cap | Daily cap |
|---|---|---|---|
| Warming | Days 0–7 | 5 / hour | 20 / day |
| Ramping | Days 7–14 | 20 / hour | 100 / day |
| Warmed | Day 14+ | No tier cap | No tier cap |
Caps apply per-domain at submission time. If you hit the limit, the relay returns a 429 (HTTP API) or 451 (SMTP). Retry after the window resets.
What counts toward the cap
Caps measure messages submitted to the relay. Whether a message ultimately delivers, bounces, or defers downstream doesn't change the count. Multi-recipient messages count once per recipient.
Tier progression
Tiers advance based on the age of your enrollment. No action required. Keep sending clean mail. Your current tier and remaining caps are visible at /account under the deliverability section.
Tips for a clean warm-up
- Send to engaged recipients first: real users who expect your mail.
- Avoid bulk sends during the first week. Spread volume across hours.
- Monitor bounces and complaints at /account. High complaint rates can lead to suspension.
- Make sure your DNS records (DKIM, SPF) are correct before sending. The relay checks these on enrollment.