Multiple Email Domains Delivering to Same Account.

I'll admit, I'm not even sure how to ask this question.  And I'm not necessarily asking for a crash course on how to do it...  rather I simply want to know if it's possible, how difficult it might be, and where to research how to do it.

My company recently decided to change it's name after 14 years.   They have decided to go with a name that is pretty long, and as such, doesn't make good marketing sense to use it in an email address.  So, they also registered a shortened variation of the new long name to use as the new email domain.  The catch is... during the transition process of the next several years, I will find myself with at least 3 (possibly more) different email domains that all need to work the same.

MyOriginal.com
TheNewLongCompanyName.com
ShortVersion.com

The boss wants all 3 to work the same.  So that email sent to bob@MyOriginal.com, or bob@TheNewLongCompanyName.com, or bob@ShortVersion.com all get delivered to the same email mailbox.  However, mail sent FROM the company will all originate from ShortVersion.com.  Moreover, we want to do this in such a way as to minimize the amount of manual set up associated with adding future users (as well as updating over 100 current users).  In other words, I'm really hoping to avoid any sort of "forwarding solution" that needs to be set up for every email user in the company.

We use Exchange 2000.

Any tips, advice, or considerations would be appreciated.  We don't have an exchange expert on staff.