What do you do about spammers using your domain

as a reply to address?

[akmac]

Got over 2000 messages on Saturday as the result of a spammer using one of my domains as a reply-to address. All of them used the same username at mydomain dot com. I'd think that my ISp would automatically block this garbage.

[Terabytes]

It's not your ISP's problem to filter email...

it's YOUR problem...

Usually there is a setting, to simply drop mail directed to non-existant accounts..

This would normally be located in your hosting control panel..under your mail properties...

hope that helps!
Tera