when autoprotect = on, outlook cant connect to exchange server

Hello,

We are trying to mirgate some of our mailboxes to exchange server 2010.

We also installed Symantec Mail Security 7.0.2.79.

We did migrate about 10 Mail boxes to this server.

But whenever we turn on Autoprotect all the clients on outlook who are on the new server, will get the error in outlook that there is no connection to the exchange server. and when we turn autoprotect off again. they work perfectly fine.

Ive been looking on the forums, but i cant seem to find anyone with our problem, let alone a solution, have you got any idea on how to solve this issue?

Thanks in advance!

With kind regards, 

Ben de Groot