- Plesk for Windows
Let's encrypt certificate for WebMail cannot be updated on Windows. Neither automatically by "Let's Encrypt Extension" task, nor manually under Plesk > Domains > example.com > Let's Encrypt > Renew . No errors appear but in IIS domain old SSL certificate is shown.
IIS does not use certificates updated via XML-RPC. This is Plesk bug with ID PPPM-5890 which will be fixed in future Plesk updates.
As a workaround:
2. Unassign an SSL certificate from webmail in Domains > example.com > Mail > Mail Settings > example.com > Webmail > None.
3. Remove this certificate from Domains > example.com > SSL/TLS Certificate .
4. Secure webmail with a new certificate according to steps from the article How to secure webmail using Let's Encrypt in Plesk Onyx