- Plesk for Windows
- Webmail is not accessible via HTTP, it is showing Plesk default page;
- Webmail may be accessed via HTTPS;
- MailEnable is used as the mail server;
- There are the following bindings in IIS > Sites > MailEnable Webmail > Bindings:
Only one type of bindings (either HTTP or HTTPS) can be enabled for webmail sites. By default, all webmail on Windows works over HTTP only.
It works this way due to certain limitations of IIS. Its performance degrades when the server has lots of domains hence a large configuration file applicationHost.config.
The bigger this file gets, the slower IIS becomes.
Starting from 12.5, Plesk was built with avoiding unnecessary additions to this file in mind.
Considering this performance aspect, during the implementation of "HTTPS support for webmail" it was decided not to add 2x bindings.
So, only one type of bindings (either HTTP or HTTPS) for webmail site was implemented.
It is recommended to use HTTPS for secure connection anyway, so the best solution would be to use webmail via HTTPS.