Answer: Find your system-wide pine.conf and put
sendmail-path=/usr/lib/sendmail -oem -oi -t
into it. (This will work with sendmail too.)
Beware that pine is neither secure nor reliable.
Answer: Put
postproc: /usr/mh/lib/spost
into each user's .mh_profile.
(This will work with sendmail too.)
Beware that MH is neither secure nor reliable.
Alternatively, install nmh, using
./configure --with-mts=sendmail
before compilation. (This will work with sendmail too.)
Answer: Put
set sendmail=/var/qmail/bin/datemail
into your .mailrc or your system-wide Mail.rc.
Beware that BSD mail is neither secure nor reliable.
Answer: There is a novice programming error in dtcm, known as ``failure to close the output side of the pipe in the child.'' I do not know whether Sun has fixed this in Solaris 2.7. Sorry.