On Tue, 13 Apr 1999, Dave Sill wrote:
qmail will always be faster than sendmail [unless you send one message
to a large number of addresses on the same remote host].
No, qmail will usually win here, too, because sendmail serializes.
Sendmail only wins when the message is huge.
Actually, if you are unfortunate enough to have a list of addresses sorted
by the right side of the @, qmail can be a big loser here. This is
because it will completely overload many remote hosts if there are a bunch
of recipients. eg. concurrencyremote = 120, you have 200 users
@somedomain, qmail will sit there with 120 connections to somedomain's
mailserver open while they all crawl along because somedomain can't handle
120 connections at once.
somedomain is poorly configured. Should qmail assume all sites are
poorly configured? Should properly configured sites suffer because
some sites are poorly run?
Geesh, this sort of crazy idealism is why qmail gets a bad name.
Please tell me how I can configure qmail so that it isn't "poorly
configured". Please give me an example of how to set it up so that a
remote site can open as many connections as it wants (which you think it
should be able to do) without monopolizing the system.
On top of that, you are still completely ignore the fact that hammering
each remote host as hard as possible, in turn, results in taking a lot
longer to deliver all the mail than if you nicely avoid hammering each
host. Part of this is due to qmail's silly 256 concurrencyremote limit,
which makes connections from the sender a very valuable commodity when
trying to send a lot of mail.
[...]
I don't know? Why does "qmail" accept connections that it cannot handle?
Mine doesn't. I restrict it via tcpserver to an acceptable,
conservative number of connections that, in my experience, the system
will be able to handle in most foreseeable circumstances.
Then do you really think it is appropriate for one remote system to
monopolize your mailer for no reason? I consider that abusive. You can
go on about "oh, there is really no way to know what you can do so you
just have to try to blast as much as you can" but that ignores the basic
principles that have worked behind all internet services for a heck of a
long time: just because you _can_ do something, doesn't mean you should do
it if it isn't a friendly thing to do.
This is great in theory. In practice, does your tcpserver setup
automatically start refusing connections when you're low on queue space or
when you know the load will be too high? I bet it doesn't.
No, but my tcpserver connection limit is sufficiently conservative
that it can almost always handle a full compliment of SMTP clients. If
it can't, so what? Chances are, a few too many SMTP connections when
the system is hosed are the least of my worries.
"if I can't accept any mail from any other systems because one system
decided to flood me with a huge amount just beacuse it thought it would be
cool to schedule deliveries that way, then it isn't a big deal"
Erm... I don't think that way.
[...]
You may have a point here. Is there a well-defined rubric within which
we can assert, "It is ill-mannered to consume all available
connections to a remote server, just because those services are
needed?" Could be, I suppose--that's a question for admins.
The point is that, in a lot of cases, they aren't needed.
If you have 50 messages to go out with 100 messages to each of 5000
hosts, the claim that it is necessary to open 100 connections at once to
any single remote server is obviously wrong.
The claim that qmail forces you to do that is also obviously wrong. IF
you don't want that to happen, don't sort your list by MX.
My claim is that qmail's behaviour ranges from extremely unfriendly to
abusive. It is easy to end up with addresses sorted by hostname for a
variety of reasons. It is a flaw in qmail that, if the address list is
sorted in such a way, it takes ~twice as long, in my experience, to send
out a large quantity of mail.
Heck, even if you had 50 messages to go to 1 host that doesn't mean
you have to open 50 connections (well, bounded only by your local
configuration and qmail's limits) to the remote host.
Of course not. What's your point? 256 is 50. If I've got 50
different messages to deliver to a single site, I sure as hell want to
use as many simultaneous connections as I can. I assume the receiving
You just said that, if qmail didn't have an arbitrary 256 simultaneous
connection limit and if your machine could handle it, then you consider it
perfectly acceptable to try to open 50 simultaneous connections.
site will behave responsibly and only accept as many as it can handle.
If the don't, that's their problem.
That sums up the problems with your attitude quite nicely, and the
problems with far too many "qmail idealists" that are more concernend
about proclaiming qmail to be the
