How can I provide the same Outlook mailbox to a different AD username?

Look at this previous EE solution. It is a commonly done task to change the username.

Hello,

Is there a particular reason you are creating a new account as opposed to just renaming the original one?

-JJ

Forward his old jdoe-c@company.com email to his new jdoe@company.com

When he writes back to people who emailed him on his old account they will see the new account and hopefully people will slowly start writing him to his new address.

You can also just keep that old email account jdoe-c@company.com, but change his AD username to simply jdoe vs jdoe-c

rmessing171 sounds like he wants to keep the old email account active for jdoe-c because i'm sure a lot of people email him there and/or it could be set as the recovery email account for certain sites if a password is forgotten.

@rmessing

simple,

1. export pst via outlook from outlook client - if you need the emails for history
2. remove smtp alias jdoe-c@domainame.com - or similar email you want to bring to the new account
3. add jdoe-c@domainname.com to  "jdoe" new mailbox.

that way when ppl email him he well get all legacy contact email addresses and all new ones

The simple solution is to just change the samaccount name, add a new primary SMTP address and change the display name, if necessary. There should be no need to create a new AD account or mailbox, unless there is a business need that isn't explained.

-JJ

The easiest way to achieve this is to disable the Exchange Mailbox, which will remove the mailbox from the user account, then run the following command in the Exchange Management Shell:

get-mailboxdatabase | clean-mailboxdatabase

You can then Reconnect the disabled jdoe-c mailbox to the new jdoe account and all the jdoe-c email history will be available to jdoe.  You can optionally add a new SMTP address for jdoc-c@yourdomain.com to capture any emails destined for the 'old' mailbox address.

Once the mailbox is added to the new account, run the above command again or the account won't work properly.

This assumes you have Exchange 2007 or higher (you haven't specified this in your question).

Alan