Source code for poplib

"""A POP3 client class.

Based on the J. Myers POP3 draft, Jan. 96

# Author: David Ascher 
#         [heavily stealing from]
# Updated: Piers Lauder  [Jul '97]
# String method conversion and test jig improvements by ESR, February 2001.
# Added the POP3_SSL class. Methods loosely based on IMAP_SSL. Hector Urtubia  Aug 2003

# Example (see the test function at the end of this file)

# Imports

import errno
import re
import socket
import sys

    import ssl
    HAVE_SSL = True
except ImportError:
    HAVE_SSL = False

__all__ = ["POP3","error_proto"]

# Exception raised when an error or invalid response is received:

[docs]class error_proto(Exception): pass

# Standard Port
POP3_PORT = 110


# Line terminators (we always output CRLF, but accept any of CRLF, LFCR, LF)
CR = b'\r'
LF = b'\n'

# maximal line length when calling readline(). This is to prevent
# reading arbitrary length lines. RFC 1939 limits POP3 line length to
# 512 characters, including CRLF. We have selected 2048 just to be on
# the safe side.
_MAXLINE = 2048

[docs]class POP3:

    """This class supports both the minimal and optional command sets.
    Arguments can be strings or integers (where appropriate)
    (e.g.: retr(1) and retr('1') both work equally well.

    Minimal Command Set:
            USER name               user(name)
            PASS string             pass_(string)
            STAT                    stat()
            LIST [msg]              list(msg = None)
            RETR msg                retr(msg)
            DELE msg                dele(msg)
            NOOP                    noop()
            RSET                    rset()
            QUIT                    quit()

    Optional Commands (some servers support these):
            RPOP name               rpop(name)
            APOP name digest        apop(name, digest)
            TOP msg n               top(msg, n)
            UIDL [msg]              uidl(msg = None)
            CAPA                    capa()
            STLS                    stls()
            UTF8                    utf8()

    Raises one exception: 'error_proto'.

    Instantiate with:
            POP3(hostname, port=110)

    NB:     the POP protocol locks the mailbox from user
            authorization until QUIT, so be sure to get in, suck
            the messages, and quit, each time you access the

            POP is a line-based protocol, which means large mail
            messages consume lots of python cycles reading them

            If it's available on your mail server, use IMAP4
            instead, it doesn't suffer from the two problems

    encoding = 'UTF-8'

    def __init__(self, host, port=POP3_PORT,
                 timeout=socket._GLOBAL_DEFAULT_TIMEOUT): = host
        self.port = port
        self._tls_established = False
        sys.audit("poplib.connect", self, host, port)
        self.sock = self._create_socket(timeout)
        self.file = self.sock.makefile('rb')
        self._debugging = 0
        self.welcome = self._getresp()

    def _create_socket(self, timeout):
        if timeout is not None and not timeout:
            raise ValueError('Non-blocking socket (timeout=0) is not supported')
        return socket.create_connection((, self.port), timeout)

    def _putline(self, line):
        if self._debugging > 1: print('*put*', repr(line))
        sys.audit("poplib.putline", self, line)
        self.sock.sendall(line + CRLF)

    # Internal: send one command to the server (through _putline())

    def _putcmd(self, line):
        if self._debugging: print('*cmd*', repr(line))
        line = bytes(line, self.encoding)

    # Internal: return one line from the server, stripping CRLF.
    # This is where all the CPU time of this module is consumed.
    # Raise error_proto('-ERR EOF') if the connection is closed.

    def _getline(self):
        line = self.file.readline(_MAXLINE + 1)
        if len(line) > _MAXLINE:
            raise error_proto('line too long')

        if self._debugging > 1: print('*get*', repr(line))
        if not line: raise error_proto('-ERR EOF')
        octets = len(line)
        # server can send any combination of CR & LF
        # however, 'readline()' returns lines ending in LF
        # so only possibilities are ...LF, ...CRLF, CR...LF
        if line[-2:] == CRLF:
            return line[:-2], octets
        if line[:1] == CR:
            return line[1:-1], octets
        return line[:-1], octets

    # Internal: get a response from the server.
    # Raise 'error_proto' if the response doesn't start with '+'.

    def _getresp(self):
        resp, o = self._getline()
        if self._debugging > 1: print('*resp*', repr(resp))
        if not resp.startswith(b'+'):
            raise error_proto(resp)
        return resp

    # Internal: get a response plus following text from the server.

    def _getlongresp(self):
        resp = self._getresp()
        list = []; octets = 0
        line, o = self._getline()
        while line != b'.':
            if line.startswith(b'..'):
                o = o-1
                line = line[1:]
            octets = octets + o
            line, o = self._getline()
        return resp, list, octets

    # Internal: send a command and get the response

    def _shortcmd(self, line):
        return self._getresp()

    # Internal: send a command and get the response plus following text

    def _longcmd(self, line):
        return self._getlongresp()

    # These can be useful:

[docs]    def getwelcome(self):
        return self.welcome

[docs]    def set_debuglevel(self, level):
        self._debugging = level

    # Here are all the POP commands:

[docs]    def user(self, user):
        """Send user name, return response

        (should indicate password required).
        return self._shortcmd('USER %s' % user)

[docs]    def pass_(self, pswd):
        """Send password, return response

        (response includes message count, mailbox size).

        NB: mailbox is locked by server from here to 'quit()'
        return self._shortcmd('PASS %s' % pswd)

[docs]    def stat(self):
        """Get mailbox status.

        Result is tuple of 2 ints (message count, mailbox size)
        retval = self._shortcmd('STAT')
        rets = retval.split()
        if self._debugging: print('*stat*', repr(rets))
        numMessages = int(rets[1])
        sizeMessages = int(rets[2])
        return (numMessages, sizeMessages)

[docs]    def list(self, which=None):
        """Request listing, return result.

        Result without a message number argument is in form
        ['response', ['mesg_num octets', ...], octets].

        Result when a message number argument is given is a
        single response: the "scan listing" for that message.
        if which is not None:
            return self._shortcmd('LIST %s' % which)
        return self._longcmd('LIST')

[docs]    def retr(self, which):
        """Retrieve whole message number 'which'.

        Result is in form ['response', ['line', ...], octets].
        return self._longcmd('RETR %s' % which)

[docs]    def dele(self, which):
        """Delete message number 'which'.

        Result is 'response'.
        return self._shortcmd('DELE %s' % which)

[docs]    def noop(self):
        """Does nothing.

        One supposes the response indicates the server is alive.
        return self._shortcmd('NOOP')

[docs]    def rset(self):
        """Unmark all messages marked for deletion."""
        return self._shortcmd('RSET')

[docs]    def quit(self):
        """Signoff: commit changes on server, unlock mailbox, close connection."""
        resp = self._shortcmd('QUIT')
        return resp

    def close(self):
        """Close the connection without assuming anything about it."""
            file = self.file
            self.file = None
            if file is not None:
            sock = self.sock
            self.sock = None
            if sock is not None:
                except OSError as exc:
                    # The server might already have closed the connection.
                    # On Windows, this may result in WSAEINVAL (error 10022):
                    # An invalid operation was attempted.
                    if (exc.errno != errno.ENOTCONN
                       and getattr(exc, 'winerror', 0) != 10022):

    #__del__ = quit

    # optional commands:

[docs]    def rpop(self, user):
        """Not sure what this does."""
        return self._shortcmd('RPOP %s' % user)

    timestamp = re.compile(br'\+OK.[^)')

[docs]    def apop(self, user, password):

        - only possible if server has supplied a timestamp in initial greeting.

                user     - mailbox user;
                password - mailbox password.

        NB: mailbox is locked by server from here to 'quit()'
        secret = bytes(password, self.encoding)
        m = self.timestamp.match(self.welcome)
        if not m:
            raise error_proto('-ERR APOP not supported by server')
        import hashlib
        digest =
        digest = hashlib.md5(digest).hexdigest()
        return self._shortcmd('APOP %s %s' % (user, digest))

[docs]    def top(self, which, howmuch):
        """Retrieve message header of message number 'which'
        and first 'howmuch' lines of message body.

        Result is in form ['response', ['line', ...], octets].
        return self._longcmd('TOP %s %s' % (which, howmuch))

[docs]    def uidl(self, which=None):
        """Return message digest (unique id) list.

        If 'which', result contains unique id for that message
        in the form 'response mesgnum uid', otherwise result is
        the list ['response', ['mesgnum uid', ...], octets]
        if which is not None:
            return self._shortcmd('UIDL %s' % which)
        return self._longcmd('UIDL')

[docs]    def utf8(self):
        """Try to enter UTF-8 mode (see RFC 6856). Returns server response.
        return self._shortcmd('UTF8')

[docs]    def capa(self):
        """Return server capabilities (RFC 2449) as a dictionary
        >>> c=poplib.POP3('localhost')
        >>> c.capa()
        {'IMPLEMENTATION': ['Cyrus', 'POP3', 'server', 'v2.2.12'],
         'TOP': [], 'LOGIN-DELAY': ['0'], 'AUTH-RESP-CODE': [],
         'EXPIRE': ['NEVER'], 'USER': [], 'STLS': [], 'PIPELINING': [],
         'UIDL': [], 'RESP-CODES': []}

        Really, according to RFC 2449, the cyrus folks should avoid
        having the implementation split into multiple arguments...
        def _parsecap(line):
            lst = line.decode('ascii').split()
            return lst[0], lst[1:]

        caps = {}
            resp = self._longcmd('CAPA')
            rawcaps = resp[1]
            for capline in rawcaps:
                capnm, capargs = _parsecap(capline)
                caps[capnm] = capargs
        except error_proto:
            raise error_proto('-ERR CAPA not supported by server')
        return caps

[docs]    def stls(self, context=None):
        """Start a TLS session on the active connection as specified in RFC 2595.

                context - a ssl.SSLContext
        if not HAVE_SSL:
            raise error_proto('-ERR TLS support missing')
        if self._tls_established:
            raise error_proto('-ERR TLS session already established')
        caps = self.capa()
        if not 'STLS' in caps:
            raise error_proto('-ERR STLS not supported by server')
        if context is None:
            context = ssl._create_stdlib_context()
        resp = self._shortcmd('STLS')
        self.sock = context.wrap_socket(self.sock,
        self.file = self.sock.makefile('rb')
        self._tls_established = True
        return resp


[docs]    class POP3_SSL(POP3):
        """POP3 client class over SSL connection

        Instantiate with: POP3_SSL(hostname, port=995, keyfile=None, certfile=None,

               hostname - the hostname of the pop3 over ssl server
               port - port number
               keyfile - PEM formatted file that contains your private key
               certfile - PEM formatted certificate chain file
               context - a ssl.SSLContext

        See the methods of the parent class POP3 for more documentation.

        def __init__(self, host, port=POP3_SSL_PORT, keyfile=None, certfile=None,
                     timeout=socket._GLOBAL_DEFAULT_TIMEOUT, context=None):
            if context is not None and keyfile is not None:
                raise ValueError("context and keyfile arguments are mutually "
            if context is not None and certfile is not None:
                raise ValueError("context and certfile arguments are mutually "
            if keyfile is not None or certfile is not None:
                import warnings
                warnings.warn("keyfile and certfile are deprecated, use a "
                              "custom context instead", DeprecationWarning, 2)
            self.keyfile = keyfile
            self.certfile = certfile
            if context is None:
                context = ssl._create_stdlib_context(certfile=certfile,
            self.context = context
            POP3.__init__(self, host, port, timeout)

        def _create_socket(self, timeout):
            sock = POP3._create_socket(self, timeout)
            sock = self.context.wrap_socket(sock,
            return sock

        def stls(self, keyfile=None, certfile=None, context=None):
            """The method unconditionally raises an exception since the
            STLS command doesn't make any sense on an already established
            SSL/TLS session.
            raise error_proto('-ERR TLS session already established')


if __name__ == "__main__":
    import sys
    a = POP3(sys.argv[1])
    (numMsgs, totalSize) = a.stat()
    for i in range(1, numMsgs + 1):
        (header, msg, octets) = a.retr(i)
        print("Message %d:" % i)
        for line in msg:
            print('   ' + line)