1. Dynamic fields in signatures, see the section of the documentation about identities
2. Instant update of counters in the quick selection panel, technically based on database notifications.
3. Optional automatic incorporation of new messages into the list. This option still needs to be activated in the Preferences->Fetching panel, since I’m not sure yet that this behaviour is desirable for large databases. It may become the default later when some more tests have been done.

On the bugs front, the counters in the quick query selection panel were not always properly updated in automatic mode, unless an explicit refresh was requested, that problem is hopefully fixed for good in 1.0.1. Also, the mime_types table was left empty by the installation by manitou-mgr --create-database, and it turned out that the user interface was likely to crash because of that when attaching a file in the composer. Both problems are also fixed.

The released files are still only source code, but in the next few weeks there should be a a debian package for manitou-mdx and Ubuntu packages for both manitou-mdx and the user interface. It doesn’t seem like the debian stable distribution has Qt-4.5, that’s why the user interface won’t be packaged for debian stable.

SELECT min(mail_id)
FROM header
WHERE position(E'\nFace: ' in lines)>0
GROUP BY
split_part(substr(lines, position(E'\nFace: ' in lines)+7, 1300), E'\n', 1)

position(…) let us know where the Face header field begins, substr(…) extracts a sufficient length of it, and split_part(…) cuts exactly the value at the first newline which marks the end of this header’s value (they’re unfolded in the header table precisely to be able to perform that kind of extraction).
Finally the GROUP BY ensures that each row in the result represents a distinct value of the Face header.

This query can be directly input into the SQL statement field of the Query Selection dialog, after which all there is to do is wait for the database engine to run it to completion.

On my sample database of about 800,000 messages from various mailing lists, it turned out that the result was a list of 176 messages. Here is a collage of a selection of the pictures (public messages only).

Here is how one particular message looks with its Face header:

Right now this is just about displaying, sometime in the future I’ll try to add Face headers to outgoing mail, and also I’d like to associate pictures to sender addresses so that messages from people who don’t use a Face header (the majority) still can be shown with a dedicated picture. I feel like even tags or sender domains (which means companies and organizations), could benefit from that kind of visual representation in certain cases.