What's the alternative? Making sure that the recipient gets the message by sending a courier to his home address?

I remember when a buddy of mine, back in the pre-email days, applied for a job at a company. About a week later, he received a letter, asking him to call them. Turns out, he forgot to put his contact info into the application, but they were interested enough to look up his name in the phone book (they also have/had street addresses were I live) and write him a letter, hoping it would reach the right person. "Always put your contact into into an application" isn't a petty rule, and neither is "use an email-provider that doesn't randomly reject messages" in my book.