Howto create Mail Relay for multiple Accounts ?

Hi all,

i just beginning with Zimbra what i want to do is using zimbra at first using my exisitng ISP Accounts 3 GMail accounts for reading and sending :
reading is fine
after reading the following post :
http://www.zimbra.com/forums/install...elay-host.html

iam able to send a mail through my ISP providers adress, but just for one entry.

Does anyone have an idea if its possible to make it working for more then one Mail Adress ?

Tanks a lot in advance

Fflax