Wouldn't it be better to just remove the dependence on time-stamp
altogether from smtpmail, since it only uses the time-stamp-yyyy-mm-dd
and time-stamp-hh:mm:ss functions, both of which are just 1-line calls
to format-time-string?

Another alternative would be to add a time-stamp-hhmmss function to
time-stamp.el and call that instead of time-stamp-hh:mm:ss from
smtpmail-send-it.

-- 
Kevin Rodgers