check for "<<>>" etc as equivalent to "<>"

first cut at DSN implementation

attempt to allow udb rewriting of envelope senders; still not
quite right, but I can't really test it without a network connection

multiple queue timeouts

don't send warning message to owner-* or *-request addresses

don't send error file with return receipts

add F=d mailer flag to turn off angle brackets on return path

break out special local mail processing (e.g., mapping to the
"prog" mailer) onto separate mailer flags

clean up Subject: line on warning messages

add "noreceipts" privacy flag

better fix to NULL q_home problem

avoid core dump if $HOME not set

restore -ba mode for UK Grey book

avoid unnecessary <sys/time.h> inclusion

Apollo/POSIX changes -- leading pathname of // can legally have
different semantics; ensure that this never happens when building pathnames

fix problem causing excessive rewriting of headers being queued

fix problem that was causing the ctladdr of whoever ran the daemon
(usually root) to own the delivery process

no need to checkfd012() in dropenvelope -- that's a legit failure mode

arrange to log sender in SMTP even if all RCPTs failed

add a "recursion level" argument to rewrite() to detect loops politely

add bufsize parameter to prescan

avoid sending WARNING message on return-receipts

fix problem that causes dead.letter to be unwritable

fix bogus implementation of name overflow limiting

sample implementation of buildfname that handles 8-bit characters