Warming up a new IP address

A new IP address has no sending history. Mailbox providers watch how it behaves before they trust it, so volume has to grow gradually.

Why it matters

Large providers limit how fast they accept mail from unknown IPs. Sending too much too soon leads to deferrals ("try again later") and, if it continues, to blocks. A gradual increase lets reputation build while you stay within what they accept.

How a ramp works

A warm-up profile sets the maximum message rate and connections per destination provider for each day. Each day the limits step up. The built-in profiles are:

• Conservative, 30 days for brand-new IPs and domains.
• Standard, 21 days for most new IPs.
• Existing reputation, 7 days when you move a sender with a good record to a new IP.

You can assign a profile to each sending address. We write the limits into your server's configuration; we never generate or send traffic ourselves.

Pausing

If your delivery logs show a spike in bounces or deferrals for a destination, the ramp holds at the current day instead of advancing, and you get an alert. Fix the cause, then let it continue.

Good habits during warm-up

• Send to people who expect your mail and recently engaged first.
• Keep SPF, DKIM, DMARC and reverse DNS correct before the first message. The DNS check helps.
• Watch your blacklist status. A listing early on is much easier to resolve than later.
• Don't switch to a new IP the moment you hit a limit. Slow down instead.