I don't know which to use. I'm on Zimbra 5.0.13 and Ubuntu 8.10

I want to setup an account for user@abc.com, but allow people to also send email to user@123.com and user@foo.net with all of the email accounts being one in the same.

I also want the user to be able to use any of the three to log into the account from the web interface.

I think domain aliasing is what I want, but I don't see an option to configure that in the gui admin pages.