Glossary

Email deliverability, defined.

Short, factual definitions you can quote. Each links to a guide or a free tool.

Email warm-up: Email warm-up is the gradual build-up of a new or unused mailbox's sending reputation, by sending a small, slowly increasing daily volume of email that recipients open, reply to and move out of spam.
Sender reputation: Sender reputation is a mailbox provider's internal assessment of how trustworthy a sending domain or IP address is, based on its history, authentication and how recipients react to its email.
Inbox placement: Inbox placement is the share of delivered email that reaches the recipient's inbox rather than the spam or junk folder.
SPF (Sender Policy Framework): SPF is a DNS TXT record that lists the mail servers allowed to send email for a domain, so receivers can check whether a message came from an authorised server.
DKIM (DomainKeys Identified Mail): DKIM is an email authentication method that adds a cryptographic signature to each message, which receivers verify with a public key published in the sender's DNS.
DMARC: DMARC is a DNS policy that tells receivers what to do with email that fails SPF and DKIM alignment for a domain (deliver, quarantine or reject) and where to send reports about it.
BIMI: BIMI (Brand Indicators for Message Identification) is a standard that lets participating mailbox providers show a sender's logo next to authenticated email.
Email blacklist (blocklist): An email blacklist, or blocklist, is a database of IP addresses or domains observed sending spam, which mail servers query through DNS to decide whether to accept or filter incoming email.
Spam rate: Spam rate is the share of delivered messages that recipients mark as spam, usually expressed as a percentage of email that reached the inbox.
Placement test (seed test): A placement test sends one email to a list of seed mailboxes at different providers and reports whether each copy landed in the inbox, a secondary tab or spam.