hmm does the alias need to receive mail?
and what mail system are you using?
sample ldif file (bad example but the important peice is mailboxid)
mailbox:foo@bar.com, dc=bar dc=com
mail from:foo@bar.com
mailboxid=12345678
passwd:foobar
mailbox:drewk@bar.com, dc=bar dc=com
mail from:foo@bar.com
mailboxid=12345678
passwd foobar
mailwill be delivered to mailboxid 12345678 when rcpt to: is either drewk or foo
either alias can log in as themselves and see the same mail
thanx,
bill