alpine doesn't respect $ATHENA_USER for sender

[geofft]

My local account on my -workstation laptop is named sipbadmin. If I export ATHENA_USER=geofft and run alpine, I correctly get to my own e-mail inbox, but replying to any message yields a message that's From: "J. J. Sipbadmin" <sipbadmin@MIT.EDU>. I could be convinced not to care about the human name, but the username needs to be $ATHENA_USER.