The email, gnarwl sent out contains strange glyphs everywhere

This happens wherever the mail contains non ASCII characters (german umlaute for example), as these are stored unicode encoded within LDAP. You have two choices here:

1. Make sure, any non ASCII character is MIME encoded. This is the proper way to do it, but may require some user discipline.
2. Use the "charset" configdirective, to translate unicode into your locale. Conversion is done using the iconv(3) routine, and therefore limited, to the encodings, it knows about. NOTE: iconv may not be available on every platform, in this case, the "charset" directive simply does nothing.

In both cases you should adjust the header.txt file accordingly.