Re: sendmail is slow for mass mail
On Tue, Apr 03, 2001 at 12:31:27AM -0400, Haim Dimermanas wrote:
> Foreword : I *really* don't want to start a flame war on that. I
> am just _very_ curious. I am currently using Exim. I don't really
> know a whole lot about it. I just think that it's nice to have a
> human readable config file and a good documentation. I am considering
> switching to qmail or postfix (I don't know which one yet) and I would
> love to know more.
i've used pretty nearly every freely available unix MTA over the last 8
or 9 years. smail for a few years, then sendmail for a few more years,
then some experimentation with zmailer and exim before settling on qmail
for a year or so. then postfix came along and i just don't use anything
else any more. i still have a few qmail systems, but only because it's
more trouble than it's worth to convert them to postfix. all my sendmail
systems got converted to postfix long ago.
qmail doesn't offer anything that postfix doesn't have, but has
licensing problems that limit it's usefulness and it's rate of
improvement.
actually, that's not quite true. the one thing that qmail has which
postfix can't do is that ezmlm only works with qmail. ezmlm is a very
nice mailing list manager in some ways...but not that much nicer than
listar or mailman that it's worth locking yourself into qmail.
i see qmail's incompatibility with other MTAs as a huge trap - and the
same kind of trap as proprietary mailers, or proprietary software in
general....once you convert to it, you're basically stuck there because
it's going to be an enormous pain to convert to anything else.
> > > The answer? qmail :)
>
> I heard that answer a LOT of times. I read (please confirm) that qmail was
> the best when it came to having a cluster of pop toasters and also that it
> was the best when it comes to virtual hosting. After all, AOL - Yahoo -
> Netscape and all are using qmail AFAIK.
>
> > actually, the answer is postfix - especially since the original message
> > said:
>
> Again, from what I read, postfix's main priority was security.
and speed. and a reasonable level of backwards compatibility with
sendmail/exim/smail/etc.
> I read your very interresting post about the differences between
> qmail and postfix when it comes to licensing issues and backward
> compatibility with sendmail. What I would like to know is your opinion
> on how postfix performs on the following points:
>
> - Ease of configuration.
postfix's main config file (/etc/postfix/main.cf) is plain english and
well commented. it's very easy to read and understand, and the default
settings are quite sensible (i.e. it will not relay by default - in
fact, you have to go to a lot of trouble to misconfigure postfix before
it will act as an open relay).
imo, it's easier to understand and configure than exim. YMMV.
exim is mostly compatible with sendmail in a very similar way - it can
use the same kinds of map files.
> I don't want to read a whole book to find out how I can enable relay
> for a range of IP.
e.g. in /etc/postfix/main.cf:
mynetworks = 127.0.0.0/8, 192.168.0.0/24
smtpd_recipient_restrictions = ..., permit_mynetworks, ...
that's simplified because there are a lot of available options. mine
looks something like this:
smtpd_recipient_restrictions = hash:/etc/postfix/junk,
reject_non_fqdn_recipient,
reject_unknown_recipient_domain,
reject_non_fqdn_sender,
reject_unknown_sender_domain,
reject_invalid_hostname,
permit_mynetworks,
reject_maps_rbl,
check_relay_domains
the order of the rules is significant...which is why, for example,
reject_maps_rbl appears AFTER permit_mynetworks. one of the RBL services
i use is the MAPS DUL and i don't want to block my own dialup users from
relaying mail through the mail server.
i also have header_checks and body_checks rules which use PCRE regexps
to block common signs of spam and viruses (e.g. block all mail to/from
friend@public.com, or all mail containing an executable attachment).
> The fact that it is sendmail compatible scares me on that one.
it doesn't use sendmail.cf or anything like it.
the compatibility is that it can use the same format files that
sendmail used to use - aliases, virtual, transports, etc.
for some, like /etc/aliases it can use the exact same file. for others,
they might need to be renamed (e.g. from /etc/mail/virtusertable to
/etc/postfix/virtual).
> - Scalability. Comparing apples to apples, does postfix provide the
> tools when it comes to hosting tens of thousands of virtual domains?
yes. it scales extremely well.
> - Reliability. Email is like dial tone these days, it's important to
> know how postfix performs on this particular topic.
well....exim's a nice little MTA for small leafnode sites - it's
basically smail done right. i wouldn't want to use it for any serious
mail server.
postfix, OTOH, i would have no hesitation in using on even the largest
mail servers. in fact, i can't think of anything else i'd even consider
using (except perhaps qmail - but the licensing issue pretty much
eliminates it from consideration).
> > postfix is also faster than qmail. and more flexible. and with much
> > better anti-spam features.
>
> Could you elaborate on that?
speedwise, postfix seems to be marginally faster (but not enough to make
a song and dance about) than qmail except for the case where you have
multiple recipients of the same message going to different addresses at
the same server. in that case, postfix sends one message total. qmail
sends one message per individual recipient. e.g. on a mailing list
with, for example, 1000 recipients at hotmail.com that makes a huge
difference....1 message with 1000 RCPT TOs versus 1000 messages.
what qmail does is useful if you want to do VERP for automatic
bounce-detection. the trouble is that you can't turn it off - it
*always* sends one message per recipient regardless of whether you want
it to or not. postfix, OTOH, allows you to send one msg per recipient if
you want but doesn't force you to.
flexibility-wise, compare the list of features of postfix vs qmail.
lots of useful stuff like posix or PCRE regexp map files, built-in LDAP
support, and lots more.
as for anti-spam features, no MTA i have ever used or looked at has
anything as good as postfix's features.
> > by contrast, postfix has an extremely active development community
> > with new features and patches being created for it all the
> > time...some of which even make it into the mainline postfix release
> > if they meet wietse venema's standards.
>
> This is a very important point. I had no idea that qmail's
> development was so slow and that postfix's was so active. Again, can
> you give more infos?
all i can suggest is that you check the mailing lists for both postfix
and qmail and make up your own mind. check also the availability of
patches and the ease of finding and using patches....and take note of
how often patches get accepted into postfix versus how often patches get
accepted into qmail.
craig
--
craig sanders <cas@taz.net.au>
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