Hey, Sorry but couldn't understand your issue. Could you please attach a screenshot so that we can help you fix this issue.

Thanks for your reply. When sending an email that has the lower case "L" in a word, it is sent as the number 1. When checking the sent mail folder, all lower case l's are shown as the number 1

Hi This may be simply the way the font displays letter 'ell' on your screen. Copy a sentence that shows the 1, and paste it into a text document (e.g. Word, Wordpad). Type a number 1 for comparison. Then try changing the font to one that displays Ls differently, such as a cursive or calligraphy font or even Verdana. Don't use Times New Roman as it does make 'ell' look like a 1. If that test proves those 111s are actually letter ell, then the fix would be to change the display font in Thunderbird settings - try a few to find one you like. Agnes