On 10/04/2022 03:54, Don Armstrong wrote:
The only real difference between a single message in an mbox and a complete mbox is From escaping.
I had an impression that MUA may decode messages from 7-bit transfer encoding including quoted-printable and base64 fragments in headers before saving .eml files. I rarely use .eml files, so I may be wrong, and I do ask for such transformation from debbugs.
Frankly, using the extension to determine mime time is bad practice, but it's a common bad practice.
In this particular case even libmagick is not a rescue, both application/mbox and message/rfc866 are detected as text/plain. Though my opinion is that thunderbird should have some option to make intention clear.