Spamjadoo
Email security glossary
Each entry opens with a definition you can quote, then the record syntax, what goes wrong, and the tool that checks it.
- Directory harvest attack
- A directory harvest attack (DHA) is a technique in which a spammer sends a burst of SMTP RCPT TO commands for guessed addresses at a target domain, such as common first names and name patterns, and records which ones the server accepts. Read more
- DKIM
- DKIM (DomainKeys Identified Mail) is an email authentication method in which the sending server signs selected headers and the body of each message with a private key, and publishes the matching public key in DNS at selector._domainkey.domain. Read more
- DMARC
- DMARC (Domain-based Message Authentication, Reporting and Conformance) is a DNS policy record at _dmarc.domain that tells receiving servers what to do with a message whose visible From domain fails both SPF and DKIM alignment: nothing, quarantine it, or reject it. Read more
- DNSBL
- A DNSBL (DNS-based blocklist, also called an RBL) is a list of IP addresses or domain names associated with spam, published as a DNS zone. Read more
- EAI
- EAI (Email Address Internationalization) is the set of standards, chiefly RFC 6530 to RFC 6533, that allow email addresses to contain Unicode characters in both the part before the @ and the domain name. Read more
- Greylisting
- Greylisting is an anti-spam technique in which a receiving server answers the first delivery attempt from an unfamiliar sender with a temporary 4xx error. Read more
- MX record
- An MX (mail exchanger) record is a DNS record that tells sending mail servers which host or hosts accept email for a domain, each with a preference number. Read more
- Reverse DNS
- Reverse DNS is the lookup that maps an IP address to a hostname, using a PTR record in the in-addr.arpa (IPv4) or ip6.arpa (IPv6) zone. Read more