Weblog entry #93 for dkg

visualizing MIME structure
Posted by dkg on Tue 29 Jan 2013 at 16:16
Better debugging tools can help us understand what's going on with MIME messages. A python scrap i wrote a couple years ago named printmimestructure has been very useful to me, so i thought i'd share it.

It reads a message from stdin, and prints a visualisation of its structure, like this:

0 dkg@alice:~$ printmimestructure < 'Maildir/cur/1269025522.M338697P12023.monkey,S=6459,W=6963:2,Sa' 
└┬╴multipart/signed 6546 bytes
 ├─╴text/plain inline 895 bytes
 └─╴application/pgp-signature inline [signature.asc] 836 bytes
0 dkg@alice:~$ 
It is being published in the notmuch repository, under devel/
git clone git://notmuchmail.org/git/notmuch
ls -l notmuch/devel/printmimestructure
It feels silly to treat this ~30 line script as its own project, but i don't know of another simple tool that does this. If you know of one, or of something similar, i'd love to hear about it in the comments (or by sending me e-mail if you prefer).

If it's useful for others, I'd be happy to contribute printmimestructure to a project of like-minded tools. Does such a project exist? Or if people think it would be handy to have in debian, i can also package it up, though that feels like it might be overkill.

and oh yeah, as always: bug reports, suggestions, complaints, and patches are welcome :)

(2013-10-09: updated to note change of location of the script, thanks to the notmuch team for adopting it)


Comments on this Entry

Posted by Anonymous (141.24.xx.xx) on Tue 29 Jan 2013 at 16:30
mutt can do this. ;-)

[ Parent | Reply to this comment ]

Posted by dkg (108.58.xx.xx) on Tue 29 Jan 2013 at 16:59
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Cool, how would i ask mutt to do that?

And wouldn't i need to set up and configure mutt to do that? last time i tried to configure mutt, it was a daylong project and i felt i'd only scratched the surface. Hopefully it's gotten better since then, though :)

Thanks for the suggestion!

[ Parent | Reply to this comment ]

Posted by Anonymous (89.247.xx.xx) on Tue 29 Jan 2013 at 17:36
Per default, "v" is mapped to view-attachments (show MIME attachments) in mutt. The latest USN shows similiarily to this:
I 1 <no description> [multipa/signed, 7bit, 3.3K]
I 2 --><no description> [text/plain, quoted, iso-8859-1, 2.0K]
A 3 -->OpenPGP digital signature [applica/pgp-signat, 7bit, 0.9K]
I 4 <no description> [text/plain, 7bit, us-ascii, 0.2K]

However, I normally use something like


use strict;
use warnings;
use Email::MIME;

my $email = join('', <STDIN>);
my $mime = Email::MIME->new($email);
print $mime->debug_structure;

when I need to access the MIME structure ...

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Posted by Anonymous (87.106.xx.xx) on Tue 29 Jan 2013 at 21:40
If you are looking for a project/package where this might fit, m(un)pack comes to mind. Created by Robert Leslie and currently maintained by Richard Braakman (Debian Maintainer is Anibal Monsalve Salazar). I am not affiliated with either of them, but they are whom I'd ask for something like that (and yes, your 30 lines are extremely useful to me :))

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Posted by Anonymous (58.178.xx.xx) on Wed 30 Jan 2013 at 09:35
package nmh has mhlist ...

mhlist -f ~/spool/p1
 msg part  type/subtype              size description                         
   0       multipart/mixed           149K
     1     multipart/alternative      10K
     1.1   text/html                 8046
     1.2   text/plain                2052
     2     application/octet-stream  102K 16_November.pdf                     
     3     text/plain                 165

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Posted by dkg (108.58.xx.xx) on Thu 31 Jan 2013 at 16:17
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Interesting, thanks. I installed nmh, but it didn't put mhlist anywhere in my $PATH. It's in /usr/bin/mh/mhlist, apparently, and when i try to run it, i get:
0 dkg@alice:/tmp$ /usr/bin/mh/mhlist -f - < /tmp/Ticket-6787.eml
mhlist: Doesn't look like nmh is installed.  Run install-mh to do so.
1 dkg@alice:/tmp$ 
and install-mh isn't in my $PATH either. Reading install-mh(8) makes it sound like i have to configure a mail user agent just to use this tool, which goes back to my earlier objection about mutt. :(

These seem like silly hoops to have to jump through for a program that just needs to read from stdin and write to stdout.

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