- The server was upgraded to Plesk Obsidian;
- Before the upgrade, there was domain without hosting, only email accounts, that were accessed through webmail via HTTP;
- After the upgrade, webmail is redirected to HTTPS as a result webmail shows invalid ssl warning.
As a workaround perform the steps below:
- Log into Plesk.
- Switch on hosting: go to Domains > example.com > Hosting settings > click Change and set Hosting type to Website hosting ;
- Install the certificate for webmail according to the article How to secure the webmail with a Let’s Encrypt certificate in Plesk ;
- Switch off hosting: go to Domains > example.com > Hosting settings > click Change and set Hosting type to No web hosting.