To be fair, you shouldn't have promised instant delivery. And saying "a couple minutes" (or even "a few") is a lot fuzzier. The kind of person who calls in af

To be fair, you shouldn't have promised instant delivery. And saying "a couple minutes" (or even "a few") is a lot fuzzier. The kind of person who calls in after 180 seconds because a few minutes have passed in the kind of person who is going to call you anyway because s/he's just neurotic. Edit: And single data points are not convincing. How many users have emailed you in 27 seconds (or something similar)? If it was just the one, I'm pretty sure it wouldn't break your business whatever your margins.