Comment 3 for bug 1166104

Same problem here, with Ubuntu 12.04 and TB 38.2.0.

The received message is really UTF8, and it's headers (and multipart heders) seem correct (the sender used Apple Mail 2.2).

If I open the message in the viewer, it displays correctly, but under View->Character Encoding, TB has selected "Western" instead of "Unicode". When forwarding the message, it gets double-encoded.

If in the viewer I change View->Character Encoding to "Unicode", the message still displays correctly, as if I didn't change anything, but now forwarding also works correctly and the encoding is preserved.

It feels as if TB would ignore the mail headers and try to autodetect the encoding, getting it wrong. This auto-detected charset is then only used with forwarding, not for displaying the mail in the viewer, or for replies. Very strange.