Ah,

It might be due to the api url SolidCP calls to communicate with Smartermail.

I will spin up a test to see if SecurityProtocolType to TLS 1.2 works as expected for smartermail.

Regards,

Marco

The reason why I cannot use an unencrypted connection is because I have configured IIS with the URL Rewrite plugin to redirect http to https for our webmail. So when SolidCP loads the site it will try to redirect to https and TLS1.2 does not work.

It looks like we are now forced to switch to TLS 1.2. Any progress on this Marco? 

I have added codes to the source that should allow TLS 1.1 and 1.2 (TLS 1.3 is not yet supported).

We aim to release a new SolidCP version in the next 3 weeks but you could test the sourcecode meanwhile if you want/ can compile asp.net.