I have a client who insists he's sending some emails to valid email addresses and the emails are bouncing (generating NDRs). I've looked at the NDRs, and sure enough each, bounce has an email address that's misspelled by one or two characters. (Sometimes the misspelling is in the name, sometimes it's in the domain.)
My client insists that he's sending to valid addresses. I've inspected his Outlook Address book, and his Outlook DAT file (formally the NK2 file), and was able to locate about 1/2 the misspelled addresses in these three locations.
Is it possible that malware is bastardizing his outbound email addresses or is bastardizing his stored emails in his Outlook contact list, his Outlook Address book, or his Outlook DAT file? Or, is it simply a lot of user error (which is a real possibility with this user).