Incorrect SSL certificate is used for mail service when Premium Email by Kolab is installed

Symptoms

• Kolab extension is used. 
• Non-default SSL certificate is set to secure mail traffic at Plesk > Tools & Settings > SSL Certificates > Certificate for securing mail;
• Email traffic still uses Plesk Default certificate;
• /etc/dovecot/private/dovecot.pem and /etc/dovecot/private/ssl-cert-and-key.pem files have different content:
  

  # md5sum /etc/dovecot/private/ssl-cert-and-key.pem /etc/dovecot/private/dovecot.pem
  232dd0e418d073758357452c825eafc1 /etc/dovecot/private/ssl-cert-and-key.pem
  5641ddb15e79c0fda43bcd7a5d5dc307 /etc/dovecot/private/dovecot.pem

Cause

This is Plesk bug with ID PPPM-7808 which is planned to be fixed in future Plesk updates.

Resolution

Workaround for Kolab version 16.3.0 and earlier

1. Connect to the server using SSH.
2. Overwrite /etc/dovecot/private/ssl-cert-and-key.pem with content from /etc/dovecot/private/dovecot.pem:
   

   # cp -f /etc/dovecot/private/dovecot.pem /etc/dovecot/private/ssl-cert-and-key.pem

Note: For Kolab version 16.3.2 there is no workaround available.