“The target principal name is incorrect” warning shown in Outlook when connecting account hosted on Plesk server

Symptoms

• While configuring Outlook mail client, the pop-up warning appears:

  The target principal name is incorrect

  

• When check the certificate via View Certificate... it shows incorrect certificate:

  This CA Root certificate is not trusted. To enable trust, install this certificate in the Trusted Root Certification Authorities store.

• The correct SSL certificate is installed for Mail Server at Tools & Settings > SSL/TLS Certificates > Certificate for securing mail [change].

• The secured mail server name is used in Outlook account settings as Incoming and Outgoing mail server names.

Cause

Unclear.

Resolution

1. Log in to Plesk.

2. Go to Tools & Settings > SSL/TLS Certificates > Certificate for securing mail [change] and click Apply to re-apply the mail server certificate.