Originally Posted by gleff
IIRC the rule is the postmark date, not date of receipt... unless you send it Fedex or similar in which case it's the date of receipt (since you could in theory call back a Fedex package to be returned).
It was delivered in person--it was to the travel agent two blocks from home. IIRC what happened is that he wrote it but when he got there they were closed and he had to go back.