Why warming matters
Warming limits how much a new domain can send while you check delivery, bounces, and complaints. Comail increases these limits over two weeks. This schedule controls traffic through Comail; it does not promise that a mailbox provider will trust your domain after 14 days.
See warming tiers for the limits and warming strategy for a migration plan.
What receivers evaluate
Section titled “What receivers evaluate”Mailbox providers use their own rules to accept, defer, reject, or filter mail. Authentication, sending history, volume, and recipient complaints can affect delivery. Providers do not publish a complete scoring formula.
Google’s sender guidelines recommend consistent sending rates, gradual volume increases, and monitoring responses. A sudden increase can cause problems even when authentication passes.
What a shared IP pool changes
Section titled “What a shared IP pool changes”Comail members use shared outbound infrastructure. Your mail uses the pool’s IP addresses, while the member-domain DKIM signatures identify your domain. The IP’s history and your domain’s history are separate factors.
A shared pool does not guarantee inbox placement. Your domain still needs correct DNS, expected mail, and a sending rate that receivers accept. Other senders’ traffic can also affect shared IP reputation.
During the warming period
Section titled “During the warming period”- Send to people who expect the message. Do not use purchased or scraped lists.
- Spread traffic through the day and stay within your hourly and daily limits.
- Check bounces and complaints. Remove invalid addresses and investigate unwanted mail.
- Check SPF, DKIM, and DMARC using the authentication guide.
The tier limits are ceilings, not sending targets. Do not send unnecessary messages just to fill them.
After the warming period
Section titled “After the warming period”The warmed tier removes the domain’s default warming cap. Your account limits, any domain overrides, and safety controls still apply. Receiver-side limits can also continue.
There is no fixed time at which all providers consider a domain trusted. Increase traffic according to observed delivery results rather than a promised reputation score or deadline.
Labels and operator overrides
Section titled “Labels and operator overrides”The relay supports label policies that can change sending limits. For example, highly_trusted can skip the warming curve, while burst_warming halves the effective hourly limit. An explicit operator tier override takes precedence over the skip-warming policy. These controls do not guarantee delivery or remove account limits.
See labels for the policy and check your account for the limits that currently apply. Do not assume a label will be issued automatically because you reach a sending cap.
Which mail counts
Section titled “Which mail counts”Normal SMTP and API submissions count toward the applicable limits, including messages sent to an address on your own domain. Reply forwarding uses a separate delivery path. See sending limits for recipient counting and reset times.