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We have an email account to which all mails that bounce are sent back to. Lately I have been seeing this particular email where it says that the Final-Recipient was I@my-domain.com. This is the full email with my-domain.com being my real domain:

This is the mail system at host mail.my-domain.com.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

                   The mail system

<I@my-domain.com> (expanded from <I>): user unknown

Final-Recipient: rfc822; I@my-domain.com
Original-Recipient: rfc822; I
Action: failed
Status: 5.1.1
Diagnostic-Code: x-unix; user unknown

Does this mean that some script on our server is constantly trying to send and email to this email address and it keeps bouncing or is there something more to it?

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It's backscatter. –  joeqwerty Apr 6 '13 at 13:27

1 Answer 1

up vote 2 down vote accepted

Most likely not - anybody can send an email using any sender email address at all, just like I could send a piece of paper mail and put your name and address on the back - and if the letter can't be delivered, it will be returned to your address instead of mine. This is called 'backscatter'.

You could protect a little against this by using SPF/DKIM, but many servers on the internet won't be checking SPF/DKIM records anyway, so it won't keep you entirely free of backscatter.

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