Or worse, using <randomchars>@somesubdomain.example.com as the SENDER address on spam to others. I once had spammers find a subdomain that accepted wildcard ema

Or worse, using <randomchars>@somesubdomain.example.com as the SENDER address on spam to others. I once had spammers find a subdomain that accepted wildcard emails, and the backscatter was just insane. Had to spend a whole day trying to make a list of valid <usernames>@ on that subdomain to whitelist to put an end to it. (Not easy if you haven't already been keeping track of which addresses you've handed out throughout the years)