Plesk Cannot Communicate with SmarterMail

Plesk relies on communicating with in order to issue the web service calls to interact with SmarterMail.
If you're encountering issues with Plesk failing to communicate to the SmarterMail web interface, please ensure that IIS is configured with a binding for port 9998 on localhost (
Please note that if you're forcing HTTPS traffic, you will need to disable this setting to ensure communication can take place. If you're manually using a URL rewrite to handle the HTTP to HTTPS redirect, please ensure your rules allow requests made to http://localhost:9998 or are not being redirected to HTTPS.