Undelivered mail returned to sender

Undelivered mail returned to sender

In the last hour, I have received 650 undelivered mail returned to sender emails for mail that I did not send.

Can anybody help? The emails are still flooding in and if this continues, I will have thousands by morning.

Have I been hacked?


This is the message I am getting:


This is the mail system at host zmmta301.webmail.cra.eircom.net.


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.