The pilot might just consider it more convenient to mail
the form sometime after the flight and rack up the YE hours;

What do YE hours buy the pilot?

Although the feeling isn't rational, I always feel a bit silly asking an FBO
to mail my liability-waiver and flight-plan forms before my Angel Flights
(there's usually no mailbox handy). I force myself to do it anyway, but I'm
certainly tempted to just bring the forms along and mailing them later.

It should be sufficient for those forms to be on the ground and in
friendly posession. It would at least show intent, and can be dropped
silently in the mailbox afterwards with nobody the wiser. Or is it
necessary for the EAA to do something with the forms for them to have
effect?

Jose
--
Money: what you need when you run out of brains.
for Email, make the obvious change in the address.