When text/* type files are attached, Content-Type headers don't have charset parameter. It's not easy to determine the charset of a text file being attached without prompting users to pick one. However, there are a couple of possibilities: 1. assume text/* file being attached is in the locale character encoding 2. assume it's in the same character encoding as the current character encoding for the mail composition 3. prompt users to pick one Anyway, we have to specify charset in Content-Type header Another complication : If it's text/html, text/css, and text/xml (with their own internal charset specification mechanism), we may be better off not adding charset parameter to C-T header. We have to check out the RFC about this.
Once I also had to attach an EUC-KR text file to a US-ASCII message body, and had to edit the file "Unsent Messages" manually to add the charset parameter. I think assumption is okay but not adequate; the user has to be able to pick one.
*** Bug 241821 has been marked as a duplicate of this bug. ***