What does the letter "L" mean in an email message?
Answer: Occasionally, you might receive an email with the letter "L" at the end of a sentence. This letter may seem out of place, but it is supposed to represent a sad face.
When someone composes an email message in Microsoft Outlook, the program converts the text emoticon :-( into a frowning face image using the Wingdings font. The frowning face is represented by the "L" character, so if you don't have the correct Wingdings font installed on your computer or device, it may show up as simply the letter L.
Similarly, Outlook converts the happy face emoticon :-) into the letter J in the Wingdings font. A less common emoticon – the neutral or indifferent face – is represented by the letter "K."