I'd find it helpful to add the following features. If you coulduseonedomain to login and authenticate for checking mail, but be abletosetanother domain to actually put on the headers for the emailaddressandthe one listed at the top of every page as the address.
The way my web hosting is setup, I have one main domain thatalltheemail accounts are setup under. The email names from theotherdomainsare just aliases.
i.e. use
User1@domain1.com for authentication, but use
User1@domain2.com in the header information, 'from' address, listed at the top of the page, etc.