The concern that I have is that John is giving us the impression that he is running the ClearOS gateway in a VMWare appliance that is running on top of a Win Client. This would require him to open port on the WAN side of the Win client that could potentially lead to breaches and defeat the purpose of having a gateway.
I also got SOGo to work with the sieve service, my mail data resides inside a firewall. I had configured the port forward correctly, my problem was the sieve socket was only accessible by the local machine. I changed the cyrus configuration for:
sieve cmd="timsieved" listen="sieve" prefork=0
Note: the above command also changes the port that sieve listens from 2000 to 4190, you can find the port list in /etc/services