That is so true... Most developers who get an account with Mailgun (http://mailgun.net) get so excited about the live email log or for some other reason... they love to fire up emails to @test.com. We have thousands of emails in our queue destined for test.com at any given moment.
Guys, please stop: what makes you think test.com can't be a real destination? :-) Actually, they don't have a mail server for that domain, but still...
Acme Labs has much the same problem. Jef's (2005) article about handling his mail is still a good read (though a bit dated now) http://acme.com/mail_filtering/
Guys, please stop: what makes you think test.com can't be a real destination? :-) Actually, they don't have a mail server for that domain, but still...