I receive a few email newsletters and mailing list digests that come to me as plain text. Almost always, the first time I open them (when they are unread), some of the lines do not have line breaks so they are not wrapped properly. Interestingly, if I close the message and reopen it, the problem is fixed and the text is wrapped properly. It often happens to text that follows quoted text, but it also happens in other places.
I've attached the source from one message that exhibited this problem. The text in the message stopped wrapping about halfway into the text.
Dave