At work, we use IMAP for our email service. This is great because I can get my email no matter where I’ve logged in, but Outlook doesn’t play nice with IMAP (probably because Microsoft wants us to use an Exchange server). So, I use Mozilla Thunderbird (or Thunderchicken as a friend of mine says).

Thunderbird is the best IMAP client that I’ve ever used, but like most email clients, it occasionally has problems with attachments sent from Outlook users. Outlook has a tendency to send attachments in the Transport Neutral Encapsulation Format (TNEF). So, if you’ve ever seen a winmail.dat attachment, this is why.

Fortunately for Thunderbird users, there’s an extension called LookOut that allows you to open files inside the winmail.dat attachment.

Crisis averted.

Other solutions for the winmail.dat problem.