Sendmail chats on sockets with the milter process and thus
doesn't become any larger. And the milters can be written
in any language. Mimedefang uses a combination of C and
perl. If you are going to run spamassassin you are stuck
with perl regardless and that's going to be your slow step
anyway so you might as well have it pre-loaded and use it
as the parser for your control steps.
Hence why I have spamassassin used to filter after the mail is queued.
Do you make mimedefang run spamassassin on all your mails before queueing?
sendmail's fork a process per connection + perl in some situations make
people have nightmares whereas the same could be done in a much more
efficient manner especially with postfix.
Like I said, most people don't bother to understand how it
currently works. Sendmail runs one milter process which
all the sendmail processes use via socket connections. In
MimeDefang's case the controlling milter is written in C
and runs multi-threaded, multiplexing connections to some
small number of slaves that do the work in single-threaded
perl. There is no extra fork per sendmail involved and
a much smaller number of perl processes than sendmails.
Also, the multiplexer manages the slave processes by
restarting them if they crash or exceed memory limits
and will inform sendmail to retry on timeouts.
Okay, I get it. lotsa sendmail processes < (one socket per sendmail
process) > single milter process < ? > perl processes
Any way you look at it, it is a much nicer design than
making the receiving process handle everything itself
or fork additional processes per message or run.
postfix does it similarly. smtpd does not handle everything itself.
You've got cleanup and trivial-rewrite to handle some stuff for smtpd
and they also pass some stuff out to proxymap to handle. Really light
stuff are handled by smtpd and the more heavy stuff is parceled out to
cleanup, trivial-rewrite and proxymap to handle.
sendmail + mimedefang is overrated. Now that postfix 2.3 is the stable
line now...postfix + mimedefang will probably be interesting depending
on how it is done...
We can pick up the discussion when/if some large volume users
equivalent to those on the MimeDefang list start using it. A
big value in using existing, working software is that you can
take advantage of other's previous experience with it.
sure.
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