Answer: Find your system-wide pine.conf and put
sendmail-path=/usr/lib/sendmail -oem -oi -tinto it. (This will work with sendmail too.) Beware that pine is neither secure nor reliable.
Answer: Put
postproc: /usr/mh/lib/spostinto 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=sendmailbefore compilation. (This will work with sendmail too.)
Answer: Put
set sendmail=/var/qmail/bin/datemailinto 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.