I would the ability to have multiple email addresses attached to a user so that when querying an IMAP account for comments etc., they will get allowed in and associated with a user. For example, if I can send from:

username@hostname.domain.com

and

username@domain.com

I want both of those associated with my account. Right now it just doesn't allow them into the system:

2005-11-07 12:02:53,095 WARN [service.util.handler.AbstractCommentHandler] This user is not in jira so can not add a comment: First Last <username@hostname.domain.com>