Default Plesk offer SSL/TLS encryption for Plesk mail server with hostname which can be configure by following this guide. What if users wish to stuck with the use of [mail.domain.com] in email client? There is alternative solution which can be done by follow these steps in Plesk panel:
2. Click Add Subdomain.
3. Specify the following:
- In the Subdomain name box, type the portion of address as [ mail ] that will be added to the domain name of your main site.
- In the Document root box, keep it as default path as it will auto generated and usually will be mail.example.com
4. Click OK and the new subdomain name [ mail.example.com ] is now shown in the list at the bottom of the screen.
5. Click "SSL/TLS Certificates" under Security under the Dashboard of the new sub-domain [ mail.example.com ]
6. Scroll to the bottom and Click "Install a free basic certificate provided by Let's Encrypt" under More options.
7. Specify the following:
- Email address : Fill in the email address to receive renewal notifications or warnings
- Tick to Secure the domain name just for [ mail.example.com ]
8. Click "Get it Free" and it will further install the Let's Encrypt SSL for [ mail.example.com ]
9. Access to the Mail tab for the primary domain [ example.com ] and click "Mail Settings"
10. Scroll down to the option "SSL/TLS certificate for mail" and choose the SSL "Lets Encrypt mail.example.com"
11. Click "OK" and you are fine to proceed with the mailbox setup with SSL/TLS in the email client. Do make sure to using appropriate ports IMAP: 993, POP3: 995, SMTP: 465.