Did you forget to submit your content?

That is the subject of the email I've had many of them bounce. 

Looking at the IP address and the email its being sent to - I see no members with the email or no users with ip...

I'd really like to know what this email subject is for and were and how it is generated.

That’s the Post before Registration follow up 

Thanks - I have decided to turn this off - the majority of email's end up getting bounced.