If you are using Mozilla's Thunderbird program for email, and you sometimes get emails with attachments that are stuck inside a winmail.dat file, have no fear, there is an easy solution.
Why do you get winmail.dat attachments?
If the sender is using Outlook and has it set to send messages in RTF format (instead of HTML - which is what everything else uses by default, including newer versions of Outlook), then anyone not using Outlook to receive the message will often get an email with parts of it missing and there will be an attached winmail.dat file, or, if there are attachments, they will be inaccessible and inside the winmail.dat attachment. More information on this and how to configure Outlook to NOT send in RTF format here.
Thunderbird solution.
If you are using Thunderbird, download and install the Lookout add-on.
With this installed, when you look at an email with attachments with a winmail.dat file, you will also see, beside it, the actual intended attachment file(s). You can click on these and save them or open them normally now.
Why do you get winmail.dat attachments?
If the sender is using Outlook and has it set to send messages in RTF format (instead of HTML - which is what everything else uses by default, including newer versions of Outlook), then anyone not using Outlook to receive the message will often get an email with parts of it missing and there will be an attached winmail.dat file, or, if there are attachments, they will be inaccessible and inside the winmail.dat attachment. More information on this and how to configure Outlook to NOT send in RTF format here.
Thunderbird solution.
If you are using Thunderbird, download and install the Lookout add-on.
With this installed, when you look at an email with attachments with a winmail.dat file, you will also see, beside it, the actual intended attachment file(s). You can click on these and save them or open them normally now.
