A
spammer places a legitimate email
address as the sender in his bulk mailout.
This is called a
"cloaked" email.
If you are unlucky enough for the Spammer to
choose your email address, (I regularly have
this problem), you will receive
undeliverable auto responses for an
email you did not send.
When the spammers IP address is blacklisted,
he will move on to another IP and a new
cloaked address.
It is a common practice and eventually these
email notifications will fade away.
You are not
affected or banned as a spammer because your IP address and the
spammers are quite different.
Disregard/Delete these cloaked email
responses.