Email messages and attachments are converted to winmail.dat files

Products

• Symantec Products

Issue/Introduction

When sending messages to users who do not use Outlook (including Web Messenger users), messages and/or their attachments may come through as MS-TNEF encoded winmail.dat files.

Cause

This will occur because the message uses the Outlook-proprietary Rich Text Format. This format is only compatible with Microsoft Outlook email clients.

Resolution

This issue is not caused by any setting on the Universal Server or within PGP Desktop. The following knowledge base article from Microsoft details how to verify your Outlook and Exchange configuration to prevent this from happening.

Microsoft links:

How to Prevent the Winmail.dat File from Being Sent to Internet Users

How to Configure Message Format Settings for a Remote Domain​