User Agent: Mozilla/5.0 (X11; Ubuntu; Linux i686; rv:15.0) Gecko/20100101 Firefox/15.0.1 Build ID: 20120907230839 Steps to reproduce: Try to reply Actual results: Thunderbird starts making unencoded UTF-8 quotations Thunderbird 5 to 15 on Ubuntu 10.04 Once in a while, Thunderbird will enter a state where every quite normal UTF-8 message being replied contains a bad quotation: UTF-8 characters are encoded as a number of bytes; otherwise said, they are not encoded. If the message is opened and the reply made after selecting the text, the quoting is all-right. It looks like the only way to stop that nuisance is to restart Thunderbird. If any such reply is saved, Thunderbird restarted and the reply reopened, the quote characters still display wrongly, showing that the problem is in the data and not the display. Attachments: test.eml : message being replied to. Re: test..png+eml : reply as displayed and saved select&Re: test.png : replying after select Expected results: Reply correctly