Email glossary
Plain-English definitions of the terms you meet when you clean an email list, set up a sending domain or read a verification result.
- DKIM (DomainKeys Identified Mail)
- DKIM (DomainKeys Identified Mail) adds a digital signature to each email so the receiver can check that it was sent by the domain and not changed on the way.
- DMARC
- DMARC (Domain-based Message Authentication, Reporting and Conformance) is a DNS policy that tells receivers what to do with email that fails authentication for your domain, and asks them to send you reports.
- Double opt-in
- Double opt-in is a signup process where the new subscriber must confirm the address by clicking a link sent to it before being added to the list.
- Email blacklist (blocklist)
- An email blacklist, also called a blocklist or DNSBL, is a public list of IP addresses or domains associated with spam, which mail servers consult before accepting a message.
- Email deliverability
- Email deliverability is the ability to get your messages into recipients' inboxes, as opposed to the spam folder or being rejected.
- Email list decay
- Email list decay is the gradual loss of valid, reachable addresses in a list over time, even when nobody adds bad data to it.
- Email validation vs email verification
- Email validation checks that an address is written correctly. Email verification goes further and asks the receiving mail server whether the mailbox exists.
- Free email provider
- A free email provider address belongs to a public mailbox service, such as Gmail, Outlook or Yahoo, rather than to a company or organization domain.
- MX record
- An MX (mail exchanger) record is a DNS entry that names the server that receives email for a domain.
- Sender reputation
- Sender reputation is how trustworthy mailbox providers consider your sending domain and IP address, based on how your past email was received.
- SMTP verification
- SMTP verification checks whether a mailbox exists by starting an email delivery with the receiving server and stopping before any message is sent.
- Spam trap
- A spam trap is an email address that should never receive legitimate mail, used by mailbox providers and blocklist operators to identify senders with poor list practices.
- SPF (Sender Policy Framework)
- SPF (Sender Policy Framework) is a DNS record that lists which servers are allowed to send email for a domain.