Ok after many hours and days of aggravation and reinstalls of Smartermail Professional 4.1 on Plesk 8.1 50 domain-250 user license. I finally got the answer I needed.
I followed the default installation and activation instructions that came with Smartermail.
I set it up and had running ok with its own SMWebserver then I turned that off and set it up under IIS as suggested.
Setup instructions
http://www.smartertools.com/Help/SmarterMail/v4/Default.aspx?p=SA&page=getting Started
Running under IIS
http://www.smartertools.com/Help/sm.../ConvertingToIIS.aspx?fromGettingStarted=true
SM 4.1 and Plesk 8.1 uses aspx (.net 2.x) that went ok
I was able to reach the new web admin under IIS for Smartermail but the Plesk control panel under Server > Plesk Components Management > SmarterMail had an icon with a yellow ! next to it and the smartermail configuration link keep coming up with this stupid error.
"Some fields are empty or contain an improper value."
This is the error when Plesk can't communicate with the Smartermail Webserver on port 9998.
Plesk has hard coded port 9998 into its software to talk to the Smartermail webserver.
The fix for me was the following 2 additional steps.
1. Goto Administrative Tools > Internet Information Services (IIS) Manager
Click on the Webs Sites folder
Right click on the web server you set up for SmarterMail to run under and select Properties. I had named mine SmarterMail
On the Website tab next to the Ip address click the advanced button to open Advanced Web Site Identification box
Click add
Select All unassigned for IP address and 9998 for port. I left host headers blank and click OK
That adds the default port to the SM webserver site for Plesk to communicate with it.
2. I then went to Control Panel > Fire Wall
Clicked on the Exceptions (middle Tab)
Click Add port
Name SmarterMail,
Port number 9998,
Type TCP
After these 2 steps which I was unable to find anywhere on swsoft or smartermail websites my Plesk panel recognized the Smartermail web server.
Smartermail tech support finally gave me this solution and said they and swsoft were working to incorporate it automatically sometime down the line for Plesk
Hope this helps