There's a downside to having a mail server accept any and all <name>@yourdomain.com: people will make uo accounts for your domain, use that as the sending addre

There's a downside to having a mail server accept any and all <name>@yourdomain.com: people will make uo accounts for your domain, use that as the sending address, and the address gets verified as "real". You then all the crap that bounces back. I now use the james+something@domain hack.