Guide

Warming up a new sending domain

No reputation is not neutral — mailbox providers throttle and spam-fold unfamiliar senders by default.

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.

Why "just use the company domain" is a trap

Sending cold mail from @company.com ties sales experiments to password resets, invoices, and recruiting mail. A ruined reputation on the apex is an all-hands incident. Use a dedicated subdomain or a sibling domain (try.company.com, getcompany.com) with its own authentication, then graduate copy that works.

Whatever you pick, authenticate it first. Warmup on a domain with no SPF is theatre.

A concrete ramp (not a law of nature)

There is no official Gmail warmup table. Teams that do not get burned tend to do something like:

Days 1–3: tens of messages per mailbox per day, mostly to people who will reply.
Days 4–14: step up by tens, not thousands.
After two to four weeks: approach the volume you actually bought the sequencer for.

If bounce rate spikes, stop increasing. Fix the list. See bounce costs.

Multiple inboxes on the same domain share reputation more than the UI suggests. Warming five mailboxes at 50/day is not the same as one mailbox at 250/day, but it is also not five free reputations.

What to send during warmup

Mail that looks like mail: short, specific, easy to reply to. Not a 1,200-word newsletter. Not an attachment. Not a tracker farm.

The best warmup recipients are people who already know you. Second best is a verified list of people you would have written anyway. Worst is a scraped catch-all dump — why.

Infrastructure checklist before day one

SPF / DKIM / DMARC present.
Custom tracking domain if the sequencer uses one, with its own DNS as the vendor specifies.
Forwarding or a real mailbox so replies are seen.
Separate IP only if you actually have the volume to warm an IP. Shared IPs are normal at the start.

What warmup will not do

It will not make an illegal list legal. It will not hide a 15% hard-bounce rate. It will not fix a From: name that is "Marketing Team" with a bit.ly in line one.

Check the new domain first

Authentication has to be in place before warmup does anything. Look up SPF, DKIM and DMARC on the domain you are about to send from.