Glossary
Sender reputation
Also called domain reputation, IP reputation.
Last reviewed 18 September 2026
What is sender reputation?
Sender reputation is what a mailbox provider has learned about the domain and the infrastructure your mail comes from, assembled from complaints, bounces, spam trap hits and how the people who receive your mail behave, and it is what decides the folder.
It is held per provider and it is not portable: Gmail knows nothing about what Yahoo thinks of you. Nobody publishes the function, and the only window most senders get is the provider’s own postmaster dashboard, which is free to whoever proves they control the domain.
Now that authentication is a floor, the identity carrying reputation is the domain in your DKIM signature rather than an IP address. That is the argument for sending from a subdomain reserved for mail: a burned subdomain can be retired in an afternoon, and a burned root domain takes your invoices and your password resets with it.
See also
- Deliverability
Deliverability is the share of the mail you send that reaches the inbox of the person you addressed it to, as distinct from delivery, which is only the share the receiving server accepted rather than bounced.
- Sending domain
A sending domain is the domain that signs and sends your mail, and it is worth separating from the sending infrastructure: the IP addresses mail leaves from are shared by default at every provider serving small senders, while the domain in the signature and the From line is yours alone.
- Spam complaint rate
A spam complaint rate is the count of people who pressed the spam or junk button divided by the mail delivered to that provider over a window it chooses, and Google and Yahoo both name 0.3 per cent as the level to stay under and 0.1 per cent as the level to aim at.
- Feedback loop
A feedback loop is an arrangement in which a mailbox provider reports back to a sender the messages its users marked as spam, so that those addresses can be suppressed immediately rather than mailed again.
Read next
This term is covered properly in Email deliverability for small senders: authentication and reputation, which is a longer piece on the subject.
Every other term is on the glossary index , the longer writing is in the guides, and what this site itself does is on the home page.
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