MTA: Mail transfer agent, refers to mail server, such as EXCHANGE, SENDMAIL
Mail system function: RESTORE ADN FORWARDġ SMTP: Simple Mail Transfer Protocol TCP 25 Sending MailĢ POP3: Third Edition Post Office Protocol TCP 110 Receiving Mail (Offline)-Standard INTERNET mail protocolģ IMAP4: The fourth edition of the message access protocol TCP 143 receiving mail (online)Ĥ RFC 822 defines the format of e-mail messages Mail system concept and planning installation