I've had a friend with an iPhone how to cancel sending an email - she's inadvertently hit the send button presumably several times when composing an email there

I've had a friend with an iPhone how to cancel sending an email - she's inadvertently hit the send button presumably several times when composing an email there. Having a "sending in 10 seconds" option may well be useful in her case. In my case I sometimes squeeze out an email at a subway station just before my connection cuts off as we head on to the next station.