POP3 Authentifizierung:

USER name
PASS string
QUIT

POP3 Übermittlung:

STAT
LIST [msg]
RETR msg
DELE msg
NOOP
RSET

IMAP
. login USER PASSWORD

SMTP Befehle:

HELO
MAIL FROM:
RCPT TO:
DATA
RSET
SEND FROM:
SOML FROM:
SAML FROM:
VRFY
EXPN
HELP [ ]
NOOP
QUIT
TURN

SMTP Meldungen:

211 System status, or system help reply
214 Help message
220 Service ready
221 Service closing transmission channel
250 Requested mail action okay, completed
251 User not local; will forward to
252 Administrative prohibition
354 Start mail input; end with .
421 Service not available, closing transmission channel
450 Requested mail action not taken: mailbox unavailable
451 Requested action aborted: local error in processing
452 Requested action not taken: insufficient system storage
500 Syntax error, command unrecognized
501 Syntax error in parameters or arguments
502 Command not implemented
503 Bad sequence of commands
504 Command parameter not implemented
550 Requested action not taken: mailbox unavailable
551 User not local; please try
552 Requested mail action aborted: exceeded storage allocation
553 Requested action not taken: mailbox name not allowed
554 Transaction failed