Winmail.dat Files: How Letter Opener Revitalizes Them

For those of us who frequently interact with Outlook users, the appearance of the winmail.dat file in our inboxes is a common frustration. This file format, used by Outlook to bundle attachments, often leaves recipients puzzled about how to access the contents.

A solution I’ve relied on is TNEF’S Enough, a no-cost tool for Mac users that was highlighted last year by Mat. Recently, I came across another tool called Letter Opener.

Letter Opener operates as a plugin for, seamlessly decoding .dat files so that the attachments are displayed just like any other.

This makes the handling of such files much more straightforward. Although Letter Opener comes with a price tag—ranging from $29.95 for a single license to $179.95 for a ten-pack—the investment might be worthwhile depending on the frequency with which you receive winmail.dat files.


Jeffrey is a dedicated writer for TUAW, bringing readers the latest news and insights on all things Apple. With a deep love for technology, Jeffrey has a knack for breaking down the complexities of the iPhone, iPad, MacBook, and Apple Watch into easy-to-understand articles. His engaging writing style and thorough research make him a trusted voice in the Apple community. When he’s not writing, Jeffrey enjoys exploring new apps and testing out the latest Apple gadgets.