overhaul status of SMTP reply codes

don't go into queue mode when you want verify mode

M_LOCAL => M_LOCALMAILER to avoid conflict with Ultrix <sys/mount.h>

try to catch exec problem with automounter

close cached MCI connections after a fork; add p (privacy) and b
(min blocks free) options; fix selfref code; clean up $#error format

let HPUX use initgroups; -DHASINITGROUPS if you have one

move the meta-characters from C0 into C1 space

clean up log levels; allow IDA-style split header/envelope rewriting;
extend arpatounix with more zones (but is this even needed?)

HPUX and OSF/1 support; fix SMTP reply codes & multiple SMTP error
problem; consider cache timeout non-permanent; be more graceful on OS
failures; log forward, alias, and userdb expansions on log lev

HPUX and OSF/1 support; fix SMTP reply codes & multiple SMTP error
problem; consider cache timeout non-permanent; be more graceful on OS
failures; log forward, alias, and userdb expansions on log level 10

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fix wildcard MX handling (option W no longer needed); fix
process title when using cached connection; many minor fixes

System 5 compatibility, misc fixes

some (iffy) changes to prevent suppressing the actual sender
during a queue run (interaction with C line in qf file)

log all instances of setting stat to EX_INTERNAL (Internal error)

more environment problems; limit resource exhaustion; fix incorrect
name in Connection timed out message; ANSI C fixes; log message sender on
returned mail during queue run; count recipients properly

more environment problems; limit resource exhaustion; fix incorrect
name in Connection timed out message; ANSI C fixes; log message sender on
returned mail during queue run; count recipients properly; fix YP code;
diagnose "message timed out" properly

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implement arpatounix; log more info; allow nested $?...$|...$.;
POSIX compatibility; handle SMTP MAIL command errors properly;
do early diagnosis of .cf errors; adjust checkpointing; misc bugs

environment handling simplification/bug fix; handle commas inside
comments; properly limit large messages in -obq mode

change checkcompat() to return an exit status

MX piggybacking, based on code from John Myers@CMU; allow checkcompat
to return -1 to mean tempfail; bug fix in m_mno computation

let checkcompat return -1 to indicate temporary failure

tuning of queueing functions as recommended by John Gardiner Myers
<jgm+@CMU.EDU>; return mail headers (no body) on messages with negative
precedence; minor other bug fixes

changes to recognize special mailer types (e.g., file) early

debugging information (print MCI structure)

Release 6

change random constants to be #defines

(partially) ANSI-fy it