Guide: sending

IP and domain warm-up for senders

Mailbox providers judge mail partly on the history of the IP address and the domain it comes from. A new IP or domain has no history, so the first weeks of volume decide how it is treated later.

Last reviewed November 4, 2026

Why warm-up exists

Spammers often move to fresh addresses and domains, so a sudden burst of mail from somewhere with no history looks risky. Providers answer it by delaying (4xx deferrals), limiting how much they accept per hour, or filtering to spam.

Warm-up is the practice of starting with a small daily volume and raising it gradually while recipients show that they want the mail. Reputation is kept both for sending IPs and for domains, so a new domain needs care even on an IP that is already warm.

How to raise volume

Start with your most engaged recipients: people who signed up or bought recently and open your mail.
Raise the daily volume in steps, and keep each step until deferrals, bounces and complaints stay low.
Send at a steady rhythm. Large gaps followed by large sends undo part of the progress.
Spread volume across providers in proportion to your list rather than sending all of one provider's recipients first.
Send transactional mail, which recipients expect, from the start; add bulk campaigns once the base is stable.

Signals to watch

Temporary deferrals that mention rate or reputation mean a provider wants you to slow down: hold the current volume or step back. Rising hard bounces mean list quality, not volume, is the problem. Spam complaints matter most; Google and Yahoo both ask senders to keep the rate reported in their tools below 0.3%.

Google Postmaster Tools and similar provider dashboards show how your domain and IPs are seen; check them during the first weeks.

When you move from another provider

Moving to a new provider usually means new sending IPs, even if your domain keeps its history. Move traffic in stages instead of all at once, beginning with transactional mail and your most engaged segment, and keep the old provider running until the new path is stable.

How Mail.Land handles warm-up

Mail.Land warms up its shared sending IPs itself, so you do not manage IP warm-up. Dedicated IPs are not available yet.

New domains follow a daily sending ramp: about 30 days on Free and 14 days on Pro, while Max plans have no ramp. Over the day's limit, API sends are refused with 429 WARMUP_LIMIT_EXCEEDED, SMTP sends get a temporary 421 reply to retry later, and campaigns and automations are paced to the next day. If you move an established domain from another provider, support can review it for a bypass.

Warm-up in the Mail.Land docs