Using '@localhost in a key attribute

Greetings -

I'm trying to use a RIPE-style database for a database here in University 
College Dublin. One of the attributes I want to use is an e-mail
address (I have an object which contains data on e-mail users). However, 
lookups for these objects are failing (although they're in the database.
Is there a problem using an '@localhost symbol (such as I get in an e-mail address)
in a key? Thanks for any and all assistance ...

 - Arthur Green
   University College Dublin Computing Services
   Tel: +353 1 706 2456  Fax: +353 1 283 7077  E-mail: arthur@localhost