There are spam email sent use my domain address but actually it not sent through my server. For example, my domain is mydomain.com somebody sent spam using email address such as aaa.mydomain.com, [email protected] but when I check return mail error, it sent through other server. I'm sure it not have been send through my domain because I log every outgoing email.
It looks like your domain name is spoofed by some script kiddies to send spam out. You need to check the header and lodge a complaint to the IP provider.
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