Text 1544, 70 rader
Skriven 1998-11-28 17:58:27 av Nima Mortazavi (2:201/250.14)
   Kommentar till text 1523 av Anders Öhrt (2:206/145.6)
Ärende: Mailserver
==================
Hej

 JB>> Varför inte qmail eller något annat _vettigt_?
 AÖ>  Vad är qmail då?

In February, 1996, Daniel J. Bernstein released the first public beta test
version of qmail, a Message Transfer Agent (MTA). One of his primary
motivations
for developing qmail was the notorious insecurity of the "standard" UNIX MTA,
sendmail. Unlike sendmail, qmail was designed to be secure in today's hostile
Internet environment. It does as little as possible in setuid programs and as
little as possible as the superuser--and does nothing setuid root. It does
separate functions in separate, mutually untrusting programs--breaking one
function won't break the whole system. It avoids error-prone parsing as much as
it can. It keeps the distinction between addresses and programs/files clear so
it won't be tricked into accessing the system in unintended ways. It is also
small and simple, yet surprisingly powerful, and was coded with almost
fanatical
care to avoid security pitfalls.


Secure:
Security isn't just a goal, but an absolute requirement. Mail delivery
is critical for users; it cannot be turned off, so it must be completely
secure.
(This is why I started writing qmail: I was sick of the security holes in
sendmail and other MTAs.)

Reliable:
qmail's straight-paper-path philosophy guarantees that a message, once
accepted into the system, will never be lost. qmail also optionally supports
maildir, a new, super-reliable user mailbox format. Maildirs, unlike mbox files
and mh folders, won't be corrupted if the system crashes during delivery. Even
better, not only can a user safely read his mail over NFS, but any number of
NFS
clients can deliver mail to him at the same time.

Efficient:
On a Pentium under BSD/OS, qmail can easily sustain 200000 local
messages per day---that's separate messages injected and delivered to mailboxes
in a real test! Although remote deliveries are inherently limited by the
slowness of DNS and SMTP, qmail overlaps 20 simultaneous deliveries by default,
so it zooms quickly through mailing lists. (This is why I finished qmail: I had
to get a big mailing list set up.)

Simple:
qmail is vastly smaller than any other Internet MTA. Some reasons why:
(1) Other MTAs have separate forwarding, aliasing, and mailing list mechanisms.
qmail has one simple forwarding mechanism that lets users handle their own
mailing lists. (2) Other MTAs offer a spectrum of delivery modes, from
fast+unsafe to slow+queued. qmail-send is instantly triggered by new items in
the queue, so the qmail system has just one delivery mode: fast+queued. (3)
Other MTAs include, in effect, a specialized version of inetd that watches the
load average. qmail's design inherently limits the machine load, so qmail-smtpd
can safely run from your system's inetd.

Replacement for sendmail:
qmail supports host and user masquerading, full host
hiding, virtual domains, null clients, list-owner rewriting, relay control,
double-bounce recording, arbitrary RFC 822 address lists, cross-host mailing
list loop detection, per-recipient checkpointing, downed host backoffs,
independent message retry schedules, etc. qmail also includes a drop-in
``sendmail'' wrapper so that it will be used transparently by your current UA

Regards,
  Nima Mortazavi
  nima.m@lycksele.net

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 * Origin: Megaskop (2:201/250.14)