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|
===============
MTA connections
===============
Outgoing connections to the outgoing mail transport agent (MTA) are mitigated
through a ``SMTPConnection`` class, which can transparently manage multiple
sessions in a single connection.
>>> from mailman.mta.connection import SMTPConnection, SMTPSConnection
>>> from lazr.config import as_boolean
The number of sessions per connections is specified when the ``SMTPConnection``
object is created, as is the host and port number of the SMTP server. Zero
means there's an unlimited number of sessions per connection.
>>> connection = SMTPConnection(
... config.mta.smtp_host, int(config.mta.smtp_port), 0)
At the start, there have been no connections to the server.
>>> smtpd.get_connection_count()
0
By sending a message to the server, a connection is opened.
::
>>> connection.sendmail('anne@example.com', ['bart@example.com'], """\
... From: anne@example.com
... To: bart@example.com
... Subject: aardvarks
...
... """)
{}
>>> smtpd.get_connection_count()
1
We can reset the connection count back to zero.
::
>>> from smtplib import SMTP
>>> def reset():
... smtpd = SMTP()
... smtpd.connect(config.mta.smtp_host, int(config.mta.smtp_port))
... smtpd.docmd('RSET')
>>> reset()
>>> smtpd.get_connection_count()
0
>>> connection.quit()
By providing an SMTP user name and password in the configuration file, Mailman
will authenticate with the mail server after each new connection.
::
>>> config.push('auth', """
... [mta]
... smtp_user: testuser
... smtp_pass: testpass
... """)
>>> connection = SMTPConnection(
... config.mta.smtp_host, int(config.mta.smtp_port), 0,
... config.mta.smtp_user, config.mta.smtp_pass)
>>> connection.sendmail('anne@example.com', ['bart@example.com'], """\
... From: anne@example.com
... To: bart@example.com
... Subject: aardvarks
...
... """)
{}
>>> print(smtpd.get_authentication_credentials())
AHRlc3R1c2VyAHRlc3RwYXNz
>>> reset()
>>> config.pop('auth')
SMTPS and STARTTLS support works through ``SMTPSConnection``
and ``STARTTLSConnection`` classes. These provide the same interface
as ``SMTPConnection``.
::
>>> connection = SMTPSConnection(
... config.mta.smtp_host, int(config.mta.smtp_port), 0,
... as_boolean(config.mta.smtp_verify_cert),
... as_boolean(config.mta.smtp_verify_hostname),
... config.mta.smtp_user, config.mta.smtp_pass)
Sessions per connection
=======================
Let's say we specify a maximum number of sessions per connection of 2. When
the third message is sent, the connection is torn down and a new one is
created.
The connection count starts at zero.
::
>>> connection = SMTPConnection(
... config.mta.smtp_host, int(config.mta.smtp_port), 2)
>>> smtpd.get_connection_count()
0
We send two messages through the ``SMTPConnection`` object. Only one connection
is opened.
::
>>> connection.sendmail('anne@example.com', ['bart@example.com'], """\
... From: anne@example.com
... To: bart@example.com
... Subject: aardvarks
...
... """)
{}
>>> smtpd.get_connection_count()
1
>>> connection.sendmail('anne@example.com', ['bart@example.com'], """\
... From: anne@example.com
... To: bart@example.com
... Subject: aardvarks
...
... """)
{}
>>> smtpd.get_connection_count()
1
The third message would cause a third session, exceeding the maximum. So the
current connection is closed and a new one opened.
::
>>> connection.sendmail('anne@example.com', ['bart@example.com'], """\
... From: anne@example.com
... To: bart@example.com
... Subject: aardvarks
...
... """)
{}
>>> smtpd.get_connection_count()
2
A fourth message does not cause a new connection to be made.
::
>>> connection.sendmail('anne@example.com', ['bart@example.com'], """\
... From: anne@example.com
... To: bart@example.com
... Subject: aardvarks
...
... """)
{}
>>> smtpd.get_connection_count()
2
But a fifth one does.
::
>>> connection.sendmail('anne@example.com', ['bart@example.com'], """\
... From: anne@example.com
... To: bart@example.com
... Subject: aardvarks
...
... """)
{}
>>> smtpd.get_connection_count()
3
No maximum
==========
A value of zero means that there is an unlimited number of sessions per
connection.
>>> connection = SMTPConnection(
... config.mta.smtp_host, int(config.mta.smtp_port), 0)
>>> reset()
Even after ten messages are sent, there's still been only one connection to
the server.
::
>>> connection.debug = True
>>> for i in range(10):
... # Ignore the results.
... results = connection.sendmail(
... 'anne@example.com', ['bart@example.com'], """\
... From: anne@example.com
... To: bart@example.com
... Subject: aardvarks
...
... """)
>>> smtpd.get_connection_count()
1
Development mode
================
By putting Mailman into development mode, you can force the recipients to a
given hard-coded address. This allows you to test Mailman without worrying
about accidental deliveries to unintended recipients.
::
>>> config.push('devmode', """
... [devmode]
... enabled: yes
... recipient: zperson@example.com
... """)
>>> smtpd.clear()
>>> connection.sendmail(
... 'anne@example.com',
... ['bart@example.com', 'cate@example.com'], """\
... From: anne@example.com
... To: bart@example.com
... Subject: aardvarks
...
... """)
{}
>>> messages = list(smtpd.messages)
>>> len(messages)
1
>>> print(messages[0].as_string())
From: anne@example.com
To: bart@example.com
Subject: aardvarks
X-Peer: ...
X-MailFrom: anne@example.com
X-RcptTo: zperson@example.com, zperson@example.com
<BLANKLINE>
<BLANKLINE>
>>> config.pop('devmode')
|
