[exim] troubleshooting overzealous delivery?

Someone who uses the "Go Daddy" SMTP relay service send a message to me,
which was received correctly. However, it KEEPS

sending it to me at 2-hour intervals, I presume due to some misunderstanding
about delivery success. I am logging a connection from

smtpout03-04.mesa1.secureserver.net which appears to deliver correctly. I
have turned up the smtp-related logging options to investigate

failing connections, but nothing but successful receipt is recorded. I
captured a session with tcpdump, but I am unable to discern any SMTP
commands when I decode the captured stream. It seems to be just a series of
random bytes, possible the attachment.



Are there any other troubleshooting tools at my disposal?