Emails in Outlook show headers instead of email content

Symptoms

• Emails in Outlook show headers instead of email content
• Courier-IMAP is used as IMAP/POP3 service
• Emails are correctly shown in Webmail
• No errors from Courier is found in maillog when emails are retrieved in Outlook

Cause

This is a Plesk bug with ID PPPM-14272

• Fixed in:
  • Plesk Obsidian 18.0.58.1

Resolution

Please consider updating your server:

• How to install Plesk updates

Workaround

There are 3 possible workarounds if Upgrading is not possible at the moment:

1. Use Webmail instead of Outlook.

2. Disable ARC by running the following commands in SSH:

   # plesk bin settings -s mail_arc_sign=false

   and

   # /usr/lib*/plesk-9.0/mail_dk_restore

   Note: This solution doesn’t fix the already “broken” emails.

3. Switch from Courier to Dovecot.

   Note: This solution properly renders the already “broken” messages.

More Information

Plesk Obsidian Change Log.