WebMail Pro PHP documentation

How to enable opening winmail.dat files

Starting from v7.3, WebMail Pro supports opening TNEF attachments which usually come from Microsoft Outlook or MS Exchange and look as winmail.dat files. In WebMail Pro, you can expand this kind of attachments to access their content and work with them the same way you work with other attachments.

To enable this functionality, you need to install the plugin. Detailed instructions are available here.