Hi all !
Well, the problem was that my version of zimbra is old...
so, the commands of mmorse were Ok (thanks for the light Mmorse), but the last one was not for my Zimbra version.
After correcting the command, everything went ok, in the several tests i've made and when doing it in the production server...
Thank you all for the replies !
The only issues i had was that i needed to add mail.domain2.com to the virtualhosts in the zimbra admin so it assumes the domain2.com and not the virtualdomain domain1.com
Everyone that uses thunderbird and outlook needed to add @domain2.com to the username.
Here are the steps i did:
Cheers all and thank you !
# quick backup
tar -jcvf zimbra.tar.bz2 zimbra/
su - zimbra
zmprov -l rd domain1.com domain2.com
zmprov createDomain domain1.com zimbraDomainType alias zimbraMailCatchAllAddress @domain1.com zimbraMailCatchAllForwardingAddress @domain2.com