Do not send mails to donotreply.com
Oh, you don't?
Well, just make sure that none of the many applications and servers you're running doesn't send mails with "email@example.com" in the mail header as a hint to the recipient that they should not reply to this mail.
Because if you don't do that, someone will get a lot of mail from your business and some of that mail (error messages, security information, etc) is of the type you don't want to leak.
I especially like the post about the Department of Homeland Security. If people like that "protect" America, then I understand why the General Public puts so much emphasis on religion and faith.
And who is this General anyway? ;-)