An email client has exactly one fundamental job: to display emails and deliver attachments reliably. Everything else is secondary.
For over a decade, the official response to TNEF has been the same stubborn, elitist excuse: "It's not an RFC standard, it's proprietary Microsoft garbage, not our problem."
Guess what? Nobody in the real world cares about your ideological war with Microsoft. When a client, a tax office, or an employer sends an email with a winmail.dat attachment containing an urgent invoice or contract, telling the user "well, the sender didn't follow open web standards" is not technical integrity—it is completely user-hostile.
Look at the competition:
Apple Mail handles it natively without blinking.
Gmail decodes it on the fly.
Thunderbird? You force your own users to rely on third-party volunteer add-ons like LookOut, only to completely break the API and break the add-on with nearly every single major release.
Software engineering has a fundamental rule known as Postel’s Law: "Be conservative in what you send, be liberal in what you accept."
If you want Thunderbird to be taken seriously as a real alternative and not just an eccentric niche project for purists, you need to make life easier for your users, not actively worse. Hiding behind moral superiority while leaving regular users stranded with unreadable emails is just plain stubborn and incompetent product management.
Stop pushing this responsibility onto volunteer add-on developers. Build a native TNEF parser directly into Thunderbird and finally fix this.
