They tried unsuccessfully to send the following email:

My friend's son is already allowed to drive a high-powered car. He's a barely legal teenage driver? What on earth is John thinking.

It was never received.

When the message was changed to say "barely a legal teenage driver," it was received just fine.

This was originally discovered when a screenwriter repeatedly tried and failed to send a script that detailed a character noticing a pornographic ad. When he changed the line, it was finally sent successfully.