Debugging POP/IMAP/SMTP With Telnet

POP3 $ telnet 110 Trying x.x.x.x … Connected to (x.x.x.x). Escape character is ‘^]’. +OK POP3 v2003.83rh server ready USER USERNAME +OK User name accepted, password please PASS PASSWORD +OK Mailbox open, 48 messages LIST +OK Mailbox scan listing follows 1 3894 2 11761 3 5499 4 13448 5 10451 RETR 5 […]

Authenticated SMTP It is important that you understand what “relaying” is and why “open relays” are a big problem on the internet. Usually Postfix accepts an email only if one of these criteria match: the recipient’s email address belongs to a user on your mail server the sender is sending the email from within the local […]