What server are you sending via eg: yahoo, comcast, att Sadly some US ISP's like AT&T and Bellsouth have started *corrupting* their customers' e-mail. If the customer sends in windows-1252 and includes for example special punctuation characters or a non-break space xA0, the ISP doesn't correctly interpret the the message as windows-1252 but as UTF-8. In UTF-8, xA0 is not valid and gets replaced by the so-called replacement character, � (0xEF 0xBF 0xBD). Since the e-mail is still windows-1252 encoded, the recipient's client displays �. Try this first: Set preference mail.strictly_mime to true. * Menu app icon > Options > Options >Advanced > 'General' tab * click on 'Config Editor' button - it will say be careful :) * in top search type : '''mime''' * look for this line: '''mail.strictly_mime''' * If set to false, double click on line to toggle value to '''true'''. * close window - top x If still a problem then try: If still using version 68 * Menu app icon > Options > Options > Display > 'Formatting' tab * click on 'Advanced' to see encoding * Set 'Unicode' on both Outgoing and Incoming * Select Check box "When possible, use the default text encoding in replies"