LDAP completion in kmail appears to use the 'cn' field, which in our setup ends up printing completing to "username <username@company.com>". Is there any way to configure kmail or address book to use a different field (such as fullName), or even better, custom text with multiple fields.

I'm running 4.4.4, BTW.

the LDAP servers configuration in the contacts section of Kontact, does not allow modification of the field to be used as the display name.

this apparently a long standing discussion point, that circles around default LDAP setups.
https://bugs.kde.org/show_bug.cgi?id=78417

you can also search around to see if there are others related to this as well. https://bugs.kde.org/buglist.cgi?quicksearch=ldap

Take care,