If you ever see this message:
MAJORDOMO ABORT (mj_majordomo)!!
HOSTILE ADDRESS (no x400 c=) email@example.com
don't worry, it's not an attack. It's just someone using an address which is slight
less common. You can tell majordomo to accept it with a configuration
setting. In /usr/local/majordomo/majordomo.cf, you will find something
# If you will be receiving x400 addresses without the c= or a[dm]=
# parts set the $no_true_x400 variable to 1. This will disable
# checking for "c=" and "a[dm]=" pieces.
$no_true_x400 = 1;
Set the flag to 1, and your problem will go away.