How to secure the webmail subdomain of a website with a Let’s Encrypt certificate?

Question

• How to secure the webmail. of a domain with a Let's Encrypt certificate?
• Is it possible to secure the webmail subdomain of a website with an SSL certificate?

Answer

Note: If the SSL It! extension is not installed on the server, the domain must have the Website hosting type set to be able to install a Let's Encrypt certificate.

In order to secure the webmail subdomain with a Let's Encrypt SSL certificate, you must perform the following steps:
Note: Before proceeding, make sure that the A record of webmail.example.com resolves to an IP address that belongs to your Plesk server.

1. Log into Plesk

2. Go to Subscriptions > example.com and make sure that a wildcard domain *.example.com or webmail.example.com are not set as subdomains for the Subscription.

   If such subdomains exist, rename or remove them, otherwise it will not be possible to issue a Let's Encrypt certificate for the webmail.example.com subdomain

3. Issue the Let's Encrypt certificate including the webmail domain under to Domains > example.com > SSL/TLS Certificates > Install > Make sure the option Secure webmail on this domain is checked > Get it free:

   Note: If it is required to use any of the other available options, make sure to check them as well
   

4. Go to Domains > example.com > Mail > Mail Settings > Verify that the newly created Let's Encrypt SSL certificate is selected in SSL/TLS certificate for webmail > Press OK to apply changes