Open Winmail.dat
Open Winmail.dat is a macOS utility designed to open and extract contents from Winmail.dat files — a proprietary format used by Microsoft Outlook and Exchange servers to encode email formatting and attachments in the TNEF (Transport Neutral Encapsulation Format). When macOS Mail users receive emails sent from Outlook in Rich Text Format, the attachments and formatting are often wrapped in a Winmail.dat file that native Mail cannot decode. Open Winmail.dat allows users to view and extract the original attachments and email content from these otherwise inaccessible files, solving a common interoperability problem between Microsoft and Apple email clients.
AI Recommendation
1 suggestionOpen Winmail.dat is a niche utility that solves a specific interoperability problem between macOS Mail and Microsoft Outlook. We could not confirm whether a native Apple Silicon build exists — the app's vendor site and search results do not clearly state the architecture status. If you rely on this tool to open Winmail.dat files regularly, contact the developer directly to ask whether a native Apple Silicon build is available or planned, since an Intel-only build will stop launching when Apple removes Rosetta 2 in macOS 28 (September 2028). As alternatives, you could use Letter Opener for macOS (which offers a 14-day free trial and integrates directly into Mail.app), TNEF's Enough (a free Mac App Store application, though it only supports up to macOS 10.15), or the online Winmail.dat reader at winmaildat.com if you only occasionally need to open these files. The most practical long-term solution is to ask senders to resend emails in HTML or plain text format instead of Rich Text Format, which prevents Winmail.dat files from being generated in the first place.
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