21.18. smtpd — SMTP Server — Python 3.3.7 documentation (original) (raw)

Source code: Lib/smtpd.py

This module offers several classes to implement SMTP (email) servers.

Several server implementations are present; one is a generic do-nothing implementation, which can be overridden, while the other two offer specific mail-sending strategies.

Additionally the SMTPChannel may be extended to implement very specific interaction behaviour with SMTP clients.

The code supports RFC 5321, plus the RFC 1870 SIZE extension.

21.18.1. SMTPServer Objects¶

class smtpd.SMTPServer(localaddr, remoteaddr, data_size_limit=33554432)¶

Create a new SMTPServer object, which binds to local address_localaddr_. It will treat remoteaddr as an upstream SMTP relayer. It inherits from asyncore.dispatcher, and so will insert itself intoasyncore‘s event loop on instantiation.

data_size_limit specifies the maximum number of bytes that will be accepted in a DATA command. A value of None or 0 means no limit.

process_message(peer, mailfrom, rcpttos, data)¶

Raise NotImplementedError exception. Override this in subclasses to do something useful with this message. Whatever was passed in the constructor as remoteaddr will be available as the _remoteaddrattribute. peer is the remote host’s address, mailfrom is the envelope originator, rcpttos are the envelope recipients and data is a string containing the contents of the e-mail (which should be in RFC 2822format).

channel_class¶

Override this in subclasses to use a custom SMTPChannel for managing SMTP clients.

21.18.2. DebuggingServer Objects¶

class smtpd.DebuggingServer(localaddr, remoteaddr)¶

Create a new debugging server. Arguments are as per SMTPServer. Messages will be discarded, and printed on stdout.

21.18.3. PureProxy Objects¶

class smtpd.PureProxy(localaddr, remoteaddr)¶

Create a new pure proxy server. Arguments are as per SMTPServer. Everything will be relayed to remoteaddr. Note that running this has a good chance to make you into an open relay, so please be careful.

21.18.4. MailmanProxy Objects¶

class smtpd.MailmanProxy(localaddr, remoteaddr)¶

Create a new pure proxy server. Arguments are as per SMTPServer. Everything will be relayed to remoteaddr, unless local mailman configurations knows about an address, in which case it will be handled via mailman. Note that running this has a good chance to make you into an open relay, so please be careful.

21.18.5. SMTPChannel Objects¶

class smtpd.SMTPChannel(server, conn, addr)¶

Create a new SMTPChannel object which manages the communication between the server and a single SMTP client.

To use a custom SMTPChannel implementation you need to override theSMTPServer.channel_class of your SMTPServer.

The SMTPChannel has the following instance variables:

smtp_server¶

Holds the SMTPServer that spawned this channel.

conn¶

Holds the socket object connecting to the client.

addr¶

Holds the address of the client, the second value returned bysocket.accept

received_lines¶

Holds a list of the line strings (decoded using UTF-8) received from the client. The lines have their "\r\n" line ending translated to"\n".

smtp_state¶

Holds the current state of the channel. This will be eitherCOMMAND initially and then DATA after the client sends a “DATA” line.

seen_greeting¶

Holds a string containing the greeting sent by the client in its “HELO”.

mailfrom¶

Holds a string containing the address identified in the “MAIL FROM:” line from the client.

rcpttos¶

Holds a list of strings containing the addresses identified in the “RCPT TO:” lines from the client.

received_data¶

Holds a string containing all of the data sent by the client during the DATA state, up to but not including the terminating "\r\n.\r\n".

fqdn¶

Holds the fully-qualified domain name of the server as returned bysocket.getfqdn().

peer¶

Holds the name of the client peer as returned by conn.getpeername()where conn is conn.

The SMTPChannel operates by invoking methods named smtp_upon reception of a command line from the client. Built into the baseSMTPChannel class are methods for handling the following commands (and responding to them appropriately):