Doubts about PF, what are the pros/cons about other MTAs?

[Glenn Steen]

On 01/07/07, Mikael Syska <mikael at syska.dk> wrote:
> Glenn Steen wrote:
> > On 01/07/07, Mikael Syska <mikael at syska.dk> wrote:
> >> Hey,
> >>
> >> Julian Field wrote:
> >> > -----BEGIN PGP SIGNED MESSAGE-----
> >> > Hash: SHA1
> >> >
> >> >
> >> >
> >> > Mikael Syska wrote:
> >> >
> >> >> [snip]
> >> >> I think I'm convinced now ... I'm going to use postfix, since no real
> >> >> arguments againts it have been made.
> >> >>
> >> >> Thanks for the time guys.
> >> >>
> >> > I'm going to release a new stable version tomorrow which includes the
> >> > recent Postfix bugfix to do with its milter support.
> >> > If you can't wait till tomorrow, then it's already on the website,
> >> > you'll just have to guess the URL for 4.61.7-1 :-)
> >> >
> >> I can wait ... I wont begin on the server until tuesday ... So no
> >> problems there.
> >>
> >> Can't wait to get my hands dirty converting the old amavisd-new setup
> >> ... some other dude had setup it up, and its a real pain to figure
> >> out ...
> >>
> >> Btw, read on a page on the internet where a person said that MS did not
> >> use the resources very good cause its spawning a new process for every
> >> mail and afterwards closing it. amavisd-new also did that in the start
> >> but changed over to daemon style ... so its not spawning a new proces
> >> every time ...
> >> Is there something about this, or did the guy just not like MS ?
> >> and if there are something about it ... will MS be changed to spawn
> >> daemons ?
> >> what are the pros/cons agints it ?
> >>
> > Don't belieeve everything said on the net....:)
> > MS runs a master and several worker children, which all (incidentally)
> > work in a daemon-like fashion, and these children will take turns
> > popping messages from the queue ... They will take as many messages as
> > necessary to form a batch (1 -> ...many messages) and work on these in
> > a "group" way... So no "single process for every message" there:-).
> > The worker children might in turn spawn children to run specific
> > functions, like AV etc, but they will still work on the whole batch as
> > such.
> So whenever MS checks the mailqueue it takes all the mails in the queue,
> and runs a batch agains them ? and then again in x seconds with a new
> batch, taking mail that havent been handled?
It's clever enough to keep track of which items is handled by some
other worker, so ... Yes, it will only handle new items... It might
look a bit strange when you have "New batch: Found 28 messages in
queue" and then followed by running a batch with only one or two
messages, but this is because other workers are handling the other
queued messages.
The decoupling of the scanning process fromthe SMTP transaction(s) and
the batch strategy are some of the design decisions Jules made that
really make things fly with MS.

> > Very efficient, very slick.
> If the above is right, this seems like its using the resources better
> than amavisd-new maybe, but theese days Ram and harddrives are very
> cheap, so if it just runs fast, i'm happy.
Resource efficiency is one of the high points of MS... The activity of
spam/av-scanning is resource hungry, by definition, so ... be happy
that MailScanner is so cleverly come together;-).

> > Of course, as with most things in MS, you can configure the amount of
> > workers to prespawn, as well as most any aspect of the process...
> > You'll see, once you start using it;)
> Think this cleared any doubts i had.
Good.
When you set this up, there is a lot of good stuff in the MailScanner
wiki... Specifics for MS+PF... and very much generally good advice in
the MAQ (although since the faq-o-matic (old MAQ) has died again, some
of the links in the new MAQ is plain dead). So have a long hard look
at http://wiki.mailscanner.info, especially the
documentation:configuration:mta:postfix subpages (look at the index to
find them).

> >
> > What motive the person stating the "one process/mail" thing has, I
> > surely can't speculate about... But it isn't correct. That much is for
> > certain.
> Can't say, lost the url... but if one process can handle multiple mails
> in the same run, it sounds great.
Yep. It *is* great;-)
With MS, you can build the best darned email scanning system you can
imagine, and in some cases.... youu couldn't even imagine how good
it'd be:-)

Cheers
-- 
-- Glenn
email: glenn < dot > steen < at > gmail < dot > com
work: glenn < dot > steen < at > ap1 < dot > se