[Mailman-Users] Slow delivery

vancleef at lostwells.net vancleef at lostwells.net
Fri Mar 9 18:25:10 CET 2007

The esteemed Brad Knowles has said:
> At 8:46 PM -0700 3/8/07, vancleef at lostwells.net wrote:
> >  Maybe this is a good time to ask just how DNS-intensive the
> >  non-sendmail MTA's are.  I am finishing off the basics on installing
> >  sendmail with Mailman, and am including some discussion of the need to
> >  install a good fast-response caching DNS server to work with sendmail.
> All MTAs I know of are pretty DNS-intensive in their operation.  The 
> more anti-spam or anti-virus filtering you do, or the more other 
> things you do to check the incoming mail, the more DNS-intensive that 
> work is going to be.
> Of course, most MTAs should give you options on how to configure them 
> so that they don't generate any DNS traffic at all, but then what 
> you're doing is effectively turning off about 99.99% of what the MTA 
> is intended to do when handling mail.
Thanks for the confirmation of what I'd suspected.  Since I've lived
with sendmail "ever since there was a sendmail" (not true, I think
more like "since 1988"), I haven't tried to work with the other MTA's.

The need for a quick, robust, and reliable name service is in the
nature of the beast, particularly when supporting a mail list server,
where one incoming mail goes out to a thousand (if not "thousands")

I'm not going to try to address LDAP, NIS or NIS+.  It takes about ten
minutes to set up the tables for named for a caching server.  That
is what I would recommend for the shop that's currenly using
/etc/hosts and remote (i.e. "somebody else's") DNS servers for
everything external.
> >  Since then I've installed master and slave servers for my Intranet
> >  LAN, but I would heartly recommend having at least a plain caching
> >  server on the box that's running the MTA.
> Years ago, this was actually a bit of a sore point amongst the 
> experts.  Some said that you were better off having a smaller number 
> of centralized caching nameservers, which handled all DNS traffic for 
> the entire network.
> Others said that you're better off having caching nameservers running 
> on each box, to spread that load out.
I'm going to snip this discussion of how to configure DNS on a site
here.  For one thing, I think that we need to keep the focus on
Mailman, and simply answer the question "do you need local name
service with Mailman?" with "Yes."  

For another, Cricket Liu and Paul Albitz, in the current 5th edition
(2006) of "DNS and BIND" have done a very good job of discussing far
more of the ins and outs of configuring DNS in a 600-page book.  They
devote an entire chapter to DNS with Unix mail.  

For Mailman support purposes, for both sendmail and DNS, I think we
need to focus on a "keep it simple" approach.  Both my site and the
former Mailman host site for my primary list are "one worker, one box,
one routable IP" sites, where Mailman, Apache, sendmail, and named all
get handled on a single node.  I also administer another ISP site 400
miles away (along with five others) that has separate boxes for login
server, mail server, web server, news server, NFS RAID server, and two 
DNS servers, all with their own routable IP's.  We did put Mailman on
that site as well.  Suffice it to say that there are a few differences
in sendmail, apache, and named configurations between those two sites, 
none of which affect Mailman.  

So I'd have to say, Mailman with sendmail and BIND DNS, yes, very easy
to do.  Follow Barry Warsaw's excellent Mailman build guide, go
through four steps to configure sendmail (I'm about to send this off
to the list), configure your DNS per Liu and Albitz, and go.  Needless
to say, doing this on an earthlink-sized system and doing it on a
one-box oldfogey.net system aren't the same in many ways that are
quite separate from Mailman considerations.  


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