classification
Title: mailbox._mboxMMDF.get_message throws away From envelope
Type: behavior Stage:
Components: email Versions: Python 3.7, Python 3.6, Python 3.5
process
Status: open Resolution:
Dependencies: Superseder:
Assigned To: Nosy List: barry, bpoaugust, r.david.murray
Priority: normal Keywords:

Created on 2017-09-19 23:27 by bpoaugust, last changed 2017-09-20 02:08 by r.david.murray.

Messages (5)
msg302570 - (view) Author: (bpoaugust) Date: 2017-09-19 23:27
https://github.com/python/cpython/blob/master/Lib/mailbox.py#L778

The code here reads the first line, but fails to save it as the unixfrom line.

Alternatively perhaps it should reset the file back to the start so the message factory has sight of the envelope.

The end result is that the envelope is lost.
msg302575 - (view) Author: R. David Murray (r.david.murray) * (Python committer) Date: 2017-09-20 00:43
It looks like it is saving it (the set_from line).  Do you have a test that proves otherwise?
msg302577 - (view) Author: (bpoaugust) Date: 2017-09-20 01:05
It is not saving the unix from line.

#!/usr/bin/env python3

with open("test.mbox",'w') as f:
    f.write("From sender@invalid Thu Nov 17 00:49:30 2016\n")
    f.write("Subject: Test\n")
    f.write("\n")
    f.write("\n")

import mailbox
messages = mailbox.mbox("test.mbox")
for msg in messages:
    print(msg.get('subject'))
    print(msg.get_from())
    print(msg.get_unixfrom())
msg302578 - (view) Author: (bpoaugust) Date: 2017-09-20 01:09
I believe that setting the file back to the start is probably the best solution.

The message as provided by e.g. postfix will include the From header and the parser is able to deal with that successfully, so I'm not sure why the mbox reader removes it before calling the parser. It only really needs to drop the trailing newline to ensure that the parser gets the same data.
msg302582 - (view) Author: R. David Murray (r.david.murray) * (Python committer) Date: 2017-09-20 02:08
It just needs to call set_unixfrom as well as set_from.  I don't know why the MMDFMessage tracks it separately, but I'm sure the author had a reason that seemed good at the time :)
History
Date User Action Args
2017-09-20 02:08:35r.david.murraysetmessages: + msg302582
2017-09-20 01:09:40bpoaugustsetmessages: + msg302578
2017-09-20 01:05:18bpoaugustsetmessages: + msg302577
2017-09-20 00:43:25r.david.murraysetmessages: + msg302575
2017-09-19 23:27:27bpoaugustcreate