I wrote once long ago about a problem where mail(1) would stop echoing
responses to me, stop processing ^D, and so on.

Nothing else was affected.  ksh is happy, trn is happy, vi is happy.

I just ran into this on BSD/OS, but I had a spare shell handy to compare
notes.

It looks like this is caused by the equivalent of
	stty -echo -echoe -icanon -pendin
happening.

Could someone else please verify that doing this is causing this
cryptic behavior?

If so, can you explain why it doesn't affect my shell, or any other
program I can think of?  Maybe this is one of those ksh magic things.

-s