wikipedia:Sender Policy Framework
See also
- Mail, SPF, DMARC, MX, DKIM, ARC, Email Authentication, Email spoofing, Sender ID
- Mail, SMTP, submission, SMTPS, POP, IMAP, StartTLS, Exim, Postfix, IRedMail, Fail2ban, Dovecot, Roundcube, DKIM, SPF, DMARC, MX,
ssmtp
, mailx
, Swaks