Solution to standard server-side signatures

I don't know if anybody has noticed, but I've written a solution for a
problem recurring on this group: appending standardized signatures to
mail messages, server side.

Using Gordon Messmer's courier-pythonfilter framework, I've
implemented a filtering module named "sigAppender" which automatically
appends signatures to text/plain and text/html MIME parts, populating
them with personalized data extracted from an LDAP directory.

It handles encoding issues automatically. It supports multiple
signature templates, selected by a dedicated LDAP attribute (you'll
have to modify your LDAP schema slightly).

It's a part of a larger package of LDAP-related pythonfilter modules
for Courier-MTA:

http://code.google.com/p/courier-pythonfilters-ldap/

The source repository is available for browsing here:
http://code.google.com/p/courier-pyt.../source/browse

The other filtering module (currently there are only 2), named
"fromNormalizer", is used for controlling the "From" headers so that a
person can only send with the mail addresses that the corresponding
LDAP entry allows (the mail attribute, and an optional
altkomPermittedSenderAddresses multi-valued custom attribute).

I think these modules solve one of the more widespread problems with
courier MTA, especially with relation to recent EU regulations
concerning electronic communications.

The downside is, the appended signatures will break any S/MIME
signatures since there is no way for the server to know the private
key of the signer.

--
Aleksander Adamowski
http://olo.org.pl