User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.17) Gecko/20080829 Firefox/2.0.0.17 Build Identifier: version 2.0.0.17 (20080914) Without the quotes of course. To show the bug, create a new message with this line: From ' Send it to yourself and then look at the copy in the Sent box and also at the copy that comes back into your Inbox. Note: I send only text email. T'bird drives me crazy as it seems to want to format it (like HTML?). For example, if a line ends in a space, the next line is screwed up. I think "From '" is just a general symptom of a more pervasive message composition problem in which the message-contents are used to keep flags - that is not good practice. Ciao -- Mark Filipak Reproducible: Always Steps to Reproduce: 1. Create a new message to be sent back to you. 2. Entire message body: From ' (i.e., 6 bytes) 3. Send it. Actual Results: "From '" (without the quotes) is replaced by ">From '" (without the quotes) thereby falsely indicating that the message body is a quote. Expected Results: "From '" (without the quotes) should insert only "From '" (without the quotes) into the message body. The 6 bytes above can actually be anywhere in the message - I shortened the test case to its minimum. When encountered, the line is marked as a quote. For example: blah-blah-blah From blah-blah-blah 'blah-blah-blah' will trigger the bug.