Intalled the mailx-8.1.1-16 security fix, seems like the
new "short list" of environment variables mailx now looks
at is a little too short, and terminal config info isn't
being seen by mailx. Practical result is that pressing the
backspace key at the & prompt prints junk instead of doing
a backspace operation -- one must literally type control-H
now to do a backspace. The shell and all other apps still
handle backspace fine, as does other RedHat machines with
older mailx's. FYI, I think this alias is what's setting
up the behavior of interest here (ts gets run in .login) ...

alias   ts      'set noglob ; eval `tset -Q -s -e^H -k^U  \!*`'