Warming up a new sending domain

A brand-new domain — or one that’s been dormant — has no sending reputation with Gmail, Outlook, or anyone else, and “no reputation” isn’t a neutral starting point. Mailbox providers throttle or spam-fold unfamiliar senders by default, precisely because a domain with no history is the profile most spam operations share.

Start small, on purpose

Send dozens a day, not thousands, for the first week or two — ideally to real contacts likely to open and reply, since engagement (opens, replies, not just non-bounces) is part of what builds reputation. Increase volume gradually over two to four weeks rather than ramping straight to your target send rate.

Watch the two numbers that matter most

Keep bounce rate under roughly 2% and spam complaints as close to zero as you can manage, for the whole warmup period — not just the first few sends. A rough week early on does lasting damage to a domain that a good week later can’t easily undo; reputation accumulates slowly and drops fast.

Clean data matters most while you have the least buffer

A domain with years of good history can absorb an occasional bad batch without real consequences. A warming domain can’t — it has the least reputation buffer of any point in its life to absorb bad addresses with. See verifying before you send and what a high bounce rate costs — both matter more, not less, on a domain that’s still building trust.