Pipelines

Pipelines process messages that have been accepted for posting, applying any modifications and also sending copies of the message to the archives, digests, NNTP, and outgoing queues. Pipelines are named and consist of a sequence of handlers, each of which is applied in turn. Unlike rules and chains, there is no way to stop a pipeline from processing the message once it’s started.

>>> mlist = create_list('test@example.com')
>>> print(mlist.posting_pipeline)
default-posting-pipeline
>>> from mailman.core.pipelines import process

For the purposes of these examples, we’ll enable just one archiver.

>>> from mailman.interfaces.mailinglist import IListArchiverSet
>>> for archiver in IListArchiverSet(mlist).archivers:
...     archiver.is_enabled = (archiver.name == 'mhonarc')

Processing a message

Messages hit the pipeline after they’ve been accepted for posting.

>>> msg = message_from_string("""\
... From: aperson@example.com
... To: test@example.com
... Subject: My first post
... Message-ID: <first>
... X-Message-ID-Hash: 4CMWUN6BHVCMHMDAOSJZ2Q72G5M32MWB
...
... First post!
... """)
>>> msgdata = {}
>>> process(mlist, msg, msgdata, mlist.posting_pipeline)

The message has been modified with additional headers, footer decorations, etc.

>>> print(msg.as_string())
From: aperson@example.com
To: test@example.com
Message-ID: <first>
X-Message-ID-Hash: 4CMWUN6BHVCMHMDAOSJZ2Q72G5M32MWB
X-Mailman-Version: ...
Precedence: list
Subject: [Test] My first post
List-Id: <test.example.com>
Archived-At: <http://lists.example.com/.../4CMWUN6BHVCMHMDAOSJZ2Q72G5M32MWB>
List-Archive: <http://lists.example.com/archives/test@example.com>
List-Help: <mailto:test-request@example.com?subject=help>
List-Post: <mailto:test@example.com>
List-Subscribe: <http://lists.example.com/listinfo/test@example.com>,
 <mailto:test-join@example.com>
List-Unsubscribe: <http://lists.example.com/listinfo/test@example.com>,
 <mailto:test-leave@example.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit

First post!
_______________________________________________
Test mailing list
test@example.com
http://lists.example.com/listinfo/test@example.com

The message metadata has information about recipients and other stuff. However there are currently no recipients for this message.

>>> dump_msgdata(msgdata)
original_sender : aperson@example.com
original_subject: My first post
recipients      : set()
stripped_subject: My first post

After pipeline processing, the message is now sitting in various other processing queues.

>>> from mailman.testing.helpers import get_queue_messages
>>> messages = get_queue_messages('archive')
>>> len(messages)
1

>>> print(messages[0].msg.as_string())
From: aperson@example.com
To: test@example.com
Message-ID: <first>
X-Message-ID-Hash: 4CMWUN6BHVCMHMDAOSJZ2Q72G5M32MWB
X-Mailman-Version: ...
Precedence: list
Subject: [Test] My first post
List-Id: <test.example.com>
...

First post!


>>> dump_msgdata(messages[0].msgdata)
_parsemsg       : False
original_sender : aperson@example.com
original_subject: My first post
recipients      : set()
stripped_subject: My first post
version         : 3

This mailing list is not linked to an NNTP newsgroup, so there’s nothing in the outgoing nntp queue.

>>> messages = get_queue_messages('nntp')
>>> len(messages)
0

The outgoing queue will hold the copy of the message that will actually get delivered to end recipients.

>>> messages = get_queue_messages('out')
>>> len(messages)
1

>>> print(messages[0].msg.as_string())
From: aperson@example.com
To: test@example.com
Message-ID: <first>
X-Message-ID-Hash: 4CMWUN6BHVCMHMDAOSJZ2Q72G5M32MWB
X-Mailman-Version: ...
Precedence: list
Subject: [Test] My first post
List-Id: <test.example.com>
...

First post!

_______________________________________________
Test mailing list
test@example.com
http://lists.example.com/listinfo/test@example.com

>>> dump_msgdata(messages[0].msgdata)
_parsemsg       : False
listid          : test.example.com
original_sender : aperson@example.com
original_subject: My first post
recipients      : set()
stripped_subject: My first post
version         : 3

There’s now one message in the digest mailbox, getting ready to be sent.

>>> from mailman.testing.helpers import digest_mbox
>>> digest = digest_mbox(mlist)
>>> sum(1 for mboxmsg in digest)
1

>>> print(list(digest)[0].as_string())
From: aperson@example.com
To: test@example.com
Message-ID: <first>
X-Message-ID-Hash: 4CMWUN6BHVCMHMDAOSJZ2Q72G5M32MWB
X-Mailman-Version: ...
Precedence: list
Subject: [Test] My first post
List-Id: <test.example.com>
...

First post!