When attachment (in recived mail or from local filesystem) have name in uft-8 enconig with twobytes symbols (f.e. russian), it passing to gpg in bad encoding. It looks like:
enigmail> C:\Program Files\GNU\GnuPG\gpg.exe --charset utf8 --batch --no-tty --status-fd 2 -e -s --trust-model always --encrypt-to 0x20FF56A1 -r 0x2F7B592720FF56A1 -u 0x20FF56A1 --passphrase-fd 0 --no-use-agent --yes -o 'somefile encfile-1'
gpg: 'somefile': No such file or directory
.....doc in reality is a simple russian name, like "Годовой отчёт.doc"
thunderbird works with those files without problems.

