usually when you get something like that it is because the HTML part of the email specifies a font name that you do not have installed. I see you are using windows 10 and the snippet you provided was apparently from a commercial email (they are usually very careful about fonts) So perhaps try holding the shift key and turning the scroll wheel on your mouse down to make the size smaller as "magnified" displays can also cause that sort of kerning issue

Hi Matt: Thank you for your reply and suggestion. Unfortunately, it had no effect. This overlapping of text is occurring on many of my HTML e-mails and, as you can see, makes them difficult to read.