We setup a customer to be able to send from different Internet domain email addresses by setting up a GW-Dom & PO for each internet domain and added ext. units (users) with the users original username (ex. test@dom1.com and test@dom2.com). This enabled the users to send either from dom1.com or dom2.com by proxying to the appropriate mailbox. Now we'd like to update the environment to 2014 but because 2014 has it's own user directory we are worried that it might no longer work. Setting up every pc to do POP3 etc... was not an option. We are worried that when updating the system it will either not accept the ext. units as users or that it will rename/delete them.

How does the upgrade process work in such cases? Will it create multiple users with the same username (different FIDs) or will it just rename/delete them?

Any help or advice would be greatly appreciated. We would like to upgrade from gw8 to gw2014.