You have to change the default Icewarp Mail Control Port from 32000 to 80 and from 32001 to the 443 (SSL).

Open your Icewarp Administration Console and go to the System -> Services and double-click the Control service. Here you can change the ports

Click the OK button. Now you can access your Icewarp Mail WebAdmin by:

http://yourIP/accounts/ or https://yourIP/accounts/

and WebMail by:

http://yourIP/mail/ or https://yourIP/mail/

You have to have an IP address with free port 80 to do that. If you are running another Web Server on all IPs on port 80 you can't change Control port in Icewarp to 80.

If you want to run Icewarp on port 80 on one IP address and IIS on port 80 on different IP address you have to disable Socket Pooling and bind your Icewarp to this one specific IP address. You can do that in the same dialog as port adjustment by checking Bind all services to specified IP addresses and specifying the addresses in the text field below.