To make sure that a text file attached to a message will be displayed correctly at the recipient's end, it requires a correct charset declaration.
Currently I don't see any chance to declare a specific charset when attaching an arbitrary text file with Roundcube. AFAIK and AFAIR, mutt for instance can do that (as being stated in a Usenet newsgroup longer ago, I did never use mutt myself).
Of course, neither Roundcube nor any other MUA can guess the correct charset. The user attaching the file needs to know (and declare) it.
Any hope that this will be possible in the nearer future?
Michael Heydekamp Co-Admin freexp.de Düsseldorf/Germany