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11.6.1 POP3 Objects

All POP3 commands are represented by methods of the same name, in lower-case.

Most commands return the response text sent by the server.

An `POP3` instance has the following methods:

`getwelcome` ()
  Returns the greeting string sent by the POP3 server.

`user` (username)
  Send user commad, response should indicate that a password is required.

`pass_` (password)
  Send password, response includes message count and mailbox size. Note: the mailbox on the server is locked until `quit()` is called.

`apop` (user, secret)
  Use the more secure APOP authentication to log into the POP3 server.

`rpop` (user)
  Use RPOP authentication (similar to UNIX r-commands) to log into POP3 server.

`stat` ()
  Get mailbox status. The result is a tuple of 2 integers: `(message count, mailbox size)`.

`list` ([which])
  Request message list, result is in the form `['response', ['mesg_num octets', ...]]`. If which is set, it is the message to list.

`retr` (which)
  Retrieve whole message number which. Result is in form `['response', ['line', ...], octets]`.

`dele` (which)
  Delete message number which.

`rset` ()
  Remove any deletion marks for the mailbox.

`noop` ()
  Do nothing. Might be used as a keep-alive.

`quit` ()
  Signoff: commit changes, unlock mailbox, drop connection.

`top` (which, howmuch)
  Retrieves the message header plus howmuch lines of the message after the header of message number which. Result is in form `['response', ['line', ...], octets]`.

`uidl` ([which])
  Return message digest (unique id) list. If which is specified, result contains unique id for that message, otherwise result is list `['response', ['mesgnum uid', ...], octets]`.