Address book in RT?

I’m not seeing anything blaringly obvious in the contribs for an address
book. My RT userbase has grown quite a bit and it’s not just IT staff
managing tickets anymore. I’ve got non-technical users that are completely
lacking in the clue dept. These are the people that don’t understand that
they must use the full internet email address when Ccing even internal
people. These are the people that somehow cannot manage to spell our company
name correctly. These are the people that insist on using a ; to sererate
email addresses.

Is there a way for me to provide an address book on the reply/comment page?
Something that could grab real name / email address from an LDAP would be