Domain reputation

Domain reputation is the score a mailbox provider assigns to a sending domain based on its history: authentication, complaint rate, bounce rate, volume patterns, and how recipients have engaged with its email. It's the main input into inbox placement.

Each provider keeps its own. Google's is driven mostly by engagement: whether recipients open, reply, delete unread, or mark as spam. Microsoft's leans more on domain age and volume consistency, which is why new domains have a harder time landing in Outlook than in Gmail.

Reputation is built slowly and lost fast. Three weeks of warmup and a few months of low-volume sending to people who reply builds it. One bad list, one spike in volume, or one week over the complaint threshold drops it, and climbing back takes longer than the fall did.

An example

A software company's outreach domain has been sending 30 emails a day per mailbox for four months, to a signal-based list, with a 0.05 percent complaint rate. Reply rates look good, so someone raises volume to 120 a day and adds a purchased list. Within ten days Gmail reputation goes from high to low in Postmaster Tools, and inbox placement follows. The domain gets rested for six weeks, and the program runs on the others.

How to protect it

Low, steady volume per mailbox. A list of people with a reason to reply. Authentication on day one. Reply-to-unsubscribe honored the same day. And more than one domain, so any single one can be rested without stopping the program.

Related terms

Email deliverability · Deliverability vs inbox placement · Sending domain · Email warmup

If you want this run for you, see our cold email agency, or cold email for B2B SaaS.