Similar to OpenPGP
DKIM
DomainKeys Identified MailS/MIME
S/MIMESender Policy Framework
Sender Policy Frameworkドメインキー
DomainKeys送信ドメイン認証
Email authenticationBitmessage
BitmessageDMARC
DMARCInbound Port 25 Blocking
Outbound Port 25 Blocking
POP before SMTP
POP before SMTPSender ID
Sender IDSMTP-AUTH
SMTP認証
バウンスメール
Bounce messageバックスキャッター (電子メール)
Backscatter (email)正引きで確認された逆引きDNSエントリ
Forward-confirmed reverse DNSRequest for Comments
Request for CommentsジョークRFC
April Fools' Day Request for Comments▲1 trendsRFC 1149
RFC 1510
RFC 2324
RFC 2550
RFC 2555
Internet Engineering Task Force
Internet Engineering Task ForceCHARGENプロトコル
Character Generator ProtocolDAYTIMEプロトコル
Daytime ProtocolDISCARDプロトコル
Discard ProtocolECHOプロトコル
Echo Protocol