Re: Microsoft's SMTP service broken/stupid

[alan () MANAWATU GEN NZ (Alan Brown)]

On Sun, 14 Mar 1999, Chris Adams wrote:

> Well, that has been fine, but now Microsoft's SMTP service comes along.
> When it gets that temporary error (for invalid reverse DNS), it tries
> again.  Fast.  Like, right away, with no delay.  This bogs down our
> servers a bit, especially the extra logging load, but eventually they go
> away.
>
> Yesterday, we got hit by four different servers running Microsoft's
> software.  One attempted delivery nearly 200,000 times, and the other
> three attempted to 30,000-40,000 times each.  This on a server that
> usually sees ~40,000 messages a day.  This filled up our logs, bogged
> everything down, and basically killed us.

What's needed is judicious tuning of these configuration items:

# load average at which we just queue messages
O QueueLA=8

# load average at which we refuse connections
O RefuseLA=12

The above two default to 8 and 12

# maximum number of children we allow at one time
O MaxDaemonChildren=12

# maximum number of new connections per second
O ConnectionRateThrottle=3

If the above two aren't defined, there are no limits.

Also useful for load control are these two items:

# deliver each queued job in a separate process?
#O ForkEachJob

# single thread deliveries (requires HostStatusDirectory)?
#O SingleThreadDelivery

AB