Some questions about migration from one configuration to another

We have a MS AD domain, where my login is my ID
username: 460256
password: xxxxx
domain: domain.com

I have an old server with a Sun Cube mail server and for ages my email has been:
e.perez@domain.com (IMAP/POP3)

We have setup a zimbra system linked to AD, so my login details are the same as the MS AD details.
user: 460256@domain.com
pass: xxxxx

I have created an alias for my account, the aliases are:

When I used the cube to send mail, all mail arrived with a From: e.perez@domain.com but now with zimbra all mail arrives with a From: 460256@domain.com.
This is expected behavior obviously, but how can I tell zimbra that I want all my outgoing email to appear From:erick.perez@domain.com instead of From:460256@domain.com ?

And, if possible, how can i massively change this for all my users on zimbra?

1- We cannot rename the AD account
2- Since the Zimbra is linked to AD the only way we know to authenticate is by using our AD credentials, and in order to use our AD credentials we had to create the new account with our numeric IDs.