Strange-looking or backwards letters, blank spaces, boxes, black diamonds, symbols and other unexpected characters can appear in any reply sent from Outlook for a variety of reasons. Understanding the source of these issues can help reduce miscommunication and improve the overall quality of your messages.
Weird characters can appear if the original email you reply to was written using a non-Latin-based language, such as Cyrillic or Arabic, or emoticons and symbols unsupported by your version of Outlook. Outlook conversion of ASCII text into curly Unicode text can also cause certain characters, such as as apostrophes and straight quotes, to not display correctly on the recipient’s end.
Weird characters also appear if you accidentally turned on the formatting marks feature that displays all of the formatting changes you made in the email as symbols. Formatting marks include right arrows to indicate tabs or indents and pilcrows to indicate new paragraphs. To turn off these marks, press “Ctrl-Shift-8” or click the button marked with a pilcrow, or paragraph mark.
The sender's email software or corrupt data transmitted by his email provider can cause weird characters. Additionally, his computer or your own could have malware. Corrupt data files can also cause saved emails you reply to at a later date to look unusual. Lastly, weird symbols will appear if you accidentally select a font style that contains them, such as Wingdings.