Help with blacklisted email

An ezine recieving bounced email from addresses not on the list

[quantikev]

I am working with a list owner who has been recieving several bounced emails a day.

Today after sending the latest ezine, over 100 bounced emails were recieved from addresses not in the subscription list.

My knowledge of the situation is limited at this point; any input about what may be going on here?

Thank you in advance..

[coopster]

Welcome to WebmasterWorld, quantikev.

Perhaps the emails are setup as forwarded mailboxes?

[JRyan]

Is there a specific error code for all, or are they different? Method of sending?