On 17 Dec 1999, Petr Novotny wrote:
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> On 17 Dec 99, at 7:28, [EMAIL PROTECTED] wrote:
> > The inability to do header rewriting without making
> > two trips through the queue causes a severe performance
> > hit, if you are doing anything other than low volume.
>
> Rewriting headers of all messages is a severe performance hit. Or
Only for sendmail. Qmail, and other mailers, can do it with very little
expense.
> can you instruct sendmail not to? I couldn't find how.
>
> > That is forwarding with only one trip through the queue.
>
> You mean reading "aliases" before delivering, and therefore
> deciding to forward immediately? Maybe with some tweaking, the
> current virtualdomains code might do that.
Also aliasing as in mailing lists. One nice feature of sendmail is that
it dedups addresses after expanding them.
This is one reason Qmail will never be used in any enterprise-scale
system. The large international 800 pound gorilla I currently consult for
uses alias-based mailing lists rather extensively. Pretty much everyone
gets subscribed to at least a dozen mailing lists as part of the company's
welcome wagon. There's a mailing list for everyone on the same floor in
the building, a mailing list for everyone on any floor in the same
building, a mailing list for everyone in all the building in the same
city, a mailing list for everyone who works on the same continent, and a
mailing list of everyone in the firm. On top of that, there are multiple
mailing lists that loosely mirror all the steps on the corporate ladder,
and mailing lists for everyone in the same business unit or IT unit.
Additionally, pretty much every IT project has its own mailing list. Every
application that the firm has installed anywhere also has a mailing list
for its users. There's even a mailing list for everyone who uses internal
and external news servers (both use authentication, and the mailing list
automatically consists of everyone who used the news server in the last 90
days).
There are individual servers which also keep track of who logs on to them,
and a mailing list is made out of that info too. This is done so that
whenever the engineering group takes a server, application, or a
particular network, down for maintenance, everyone who can potentially be
affected by the down time is aware of it.
Now, you can't run something like that with Qmail and ezmlm. Pretty much
any kind of memo is sent out to at least three or four mailing lists.
Since everything is kept as, basically, one huge mail alias file, sendmail
dedups the recipient list after expanding it (and, yes, as long as you run
a sendmail farm on a large enough ring of big honking UNIX boxes with more
CPUs than most people have fingers on their hands, the performance is
quite acceptable).
This is an absolute requirement for any enterprise-scale environment. If
everyone started to get three or four copies of the same memo, this would
get old pretty quickly.
