Hi again and many many thanks for your quick answers!
I answered you earlier and i updated my profile which the information you asked for

But my mistake, because i edited a post instead writing a new one.

1-yes, i have access via ssh and i managed to get into zimbra configuration files.
2-i do not want to move to another MTA, because i guess nothing is wrong with zimbra, but:
a) the server is not in production yet because the last admin went away, and ,after the tests i run and after the how-to-s i have read, i will need for all the users with MS Outlook this connector
b) i will have to move to something else IF i will not be able to get along with this one.
3- i have even installed Zimbra desktop, tring to bypass the MS Outlook, but it also not working like i supposed (calendar not updating etc...)..