21.14. poplib
— POP3 protocol client¶
Source code: Lib/poplib.py
This module defines a class, POP3
, which encapsulates a connection to a
POP3 server and implements the protocol as defined in RFC 1939. The
POP3
class supports both the minimal and optional command sets from
RFC 1939. The POP3
class also supports the STLS
command introduced
in RFC 2595 to enable encrypted communication on an already established connection.
Additionally, this module provides a class POP3_SSL
, which provides
support for connecting to POP3 servers that use SSL as an underlying protocol
layer.
Note that POP3, though widely supported, is obsolescent. The implementation
quality of POP3 servers varies widely, and too many are quite poor. If your
mailserver supports IMAP, you would be better off using the
imaplib.IMAP4
class, as IMAP servers tend to be better implemented.
The poplib
module provides two classes:
-
class
poplib.
POP3
(host, port=POP3_PORT[, timeout])¶ This class implements the actual POP3 protocol. The connection is created when the instance is initialized. If port is omitted, the standard POP3 port (110) is used. The optional timeout parameter specifies a timeout in seconds for the connection attempt (if not specified, the global default timeout setting will be used).
-
class
poplib.
POP3_SSL
(host, port=POP3_SSL_PORT, keyfile=None, certfile=None, timeout=None, context=None)¶ This is a subclass of
POP3
that connects to the server over an SSL encrypted socket. If port is not specified, 995, the standard POP3-over-SSL port is used. timeout works as in thePOP3
constructor. context is an optionalssl.SSLContext
object which allows bundling SSL configuration options, certificates and private keys into a single (potentially long-lived) structure. Please read Security considerations for best practices.keyfile and certfile are a legacy alternative to context - they can point to PEM-formatted private key and certificate chain files, respectively, for the SSL connection.
Distinto en la versión 3.2: context parameter added.
Distinto en la versión 3.4: The class now supports hostname check with
ssl.SSLContext.check_hostname
and Server Name Indication (seessl.HAS_SNI
).
One exception is defined as an attribute of the poplib
module:
-
exception
poplib.
error_proto
¶ Exception raised on any errors from this module (errors from
socket
module are not caught). The reason for the exception is passed to the constructor as a string.
Ver también
- Module
imaplib
- The standard Python IMAP module.
- Frequently Asked Questions About Fetchmail
- The FAQ for the fetchmail POP/IMAP client collects information on POP3 server variations and RFC noncompliance that may be useful if you need to write an application based on the POP protocol.
21.14.1. POP3 Objects¶
All POP3 commands are represented by methods of the same name, in lower-case; most return the response text sent by the server.
An POP3
instance has the following methods:
-
POP3.
set_debuglevel
(level)¶ Set the instance’s debugging level. This controls the amount of debugging output printed. The default,
0
, produces no debugging output. A value of1
produces a moderate amount of debugging output, generally a single line per request. A value of2
or higher produces the maximum amount of debugging output, logging each line sent and received on the control connection.
-
POP3.
getwelcome
()¶ Returns the greeting string sent by the POP3 server.
-
POP3.
capa
()¶ Query the server’s capabilities as specified in RFC 2449. Returns a dictionary in the form
{'name': ['param'...]}
.Nuevo en la versión 3.4.
-
POP3.
user
(username)¶ Send user command, response should indicate that a password is required.
-
POP3.
pass_
(password)¶ Send password, response includes message count and mailbox size. Note: the mailbox on the server is locked until
quit()
is called.
-
POP3.
apop
(user, secret)¶ Use the more secure APOP authentication to log into the POP3 server.
-
POP3.
rpop
(user)¶ Use RPOP authentication (similar to UNIX r-commands) to log into POP3 server.
-
POP3.
stat
()¶ Get mailbox status. The result is a tuple of 2 integers:
(message count, mailbox size)
.
-
POP3.
list
([which])¶ Request message list, result is in the form
(response, ['mesg_num octets', ...], octets)
. If which is set, it is the message to list.
-
POP3.
retr
(which)¶ Retrieve whole message number which, and set its seen flag. Result is in form
(response, ['line', ...], octets)
.
-
POP3.
dele
(which)¶ Flag message number which for deletion. On most servers deletions are not actually performed until QUIT (the major exception is Eudora QPOP, which deliberately violates the RFCs by doing pending deletes on any disconnect).
-
POP3.
rset
()¶ Remove any deletion marks for the mailbox.
-
POP3.
noop
()¶ Do nothing. Might be used as a keep-alive.
-
POP3.
quit
()¶ Signoff: commit changes, unlock mailbox, drop connection.
-
POP3.
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)
.The POP3 TOP command this method uses, unlike the RETR command, doesn’t set the message’s seen flag; unfortunately, TOP is poorly specified in the RFCs and is frequently broken in off-brand servers. Test this method by hand against the POP3 servers you will use before trusting it.
-
POP3.
uidl
(which=None)¶ Return message digest (unique id) list. If which is specified, result contains the unique id for that message in the form
'response mesgnum uid
, otherwise result is list(response, ['mesgnum uid', ...], octets)
.
-
POP3.
utf8
()¶ Try to switch to UTF-8 mode. Returns the server response if successful, raises
error_proto
if not. Specified in RFC 6856.Nuevo en la versión 3.5.
-
POP3.
stls
(context=None)¶ Start a TLS session on the active connection as specified in RFC 2595. This is only allowed before user authentication
context parameter is a
ssl.SSLContext
object which allows bundling SSL configuration options, certificates and private keys into a single (potentially long-lived) structure. Please read Security considerations for best practices.This method supports hostname checking via
ssl.SSLContext.check_hostname
and Server Name Indication (seessl.HAS_SNI
).Nuevo en la versión 3.4.
Instances of POP3_SSL
have no additional methods. The interface of this
subclass is identical to its parent.
21.14.2. POP3 Example¶
Here is a minimal example (without error checking) that opens a mailbox and retrieves and prints all messages:
import getpass, poplib
M = poplib.POP3('localhost')
M.user(getpass.getuser())
M.pass_(getpass.getpass())
numMessages = len(M.list()[1])
for i in range(numMessages):
for j in M.retr(i+1)[1]:
print(j)
At the end of the module, there is a test section that contains a more extensive example of usage.