RE: Re: Internet Problems (was KAT 5)

["K. C. Li" <li@xxxxxxx>]

On Sun, 20 May 2001, Keith Doxey wrote:

> I dont believe all the problems were due to BTInternet because I tried
> different dialups using Freeserve and Freenetname and there were
> connectivity failures there too. I think something on the main
Internet
> backbones has been severly knackered, or there is just too much
traffic for
> the current infrastructure. Some sites were perfectly reachable,
> others....not a hope.

As we run our own e-mail server and not via another ISP, we can see where
the problems are in terms of e-mail delivery. BT Internet is by far the
worst so far. From our logs, it appears that BTI have two e-mail servers,
"stargate" and "moongate", that handle their e-mails. A
lot of the time,
either one or both of them would refuse to accept e-mails for hours. This
is not a connectivity problem as our e-mail server was able to communicate
with them but just received connection refused responses.

This connection refusal is sometimes the cause of e-mails arriving out of
sequence. The reason is that some e-mail servers (eg. postfix) have
intelligence built-in to minimise e-mail delays and to protect the
destination servers from undue overload. If an e-mail cannot be delivered
to the destination, it is queued for an increasing waiting period before
retry. This is designed to minimise overloading the destination server
when it comes back on line (and cause it to overload again). While the
e-mail is being queued, attempts to deliver any new e-mail to the same
destination would continue and may succeed if the refusal is sporadic. So
it is possible for new e-mails to arrive before the old ones that are
still waiting in a queue.

Regards,

Kwong Li
li@xxxxxxx
Laser Business Systems Ltd.
http://www.laser.com




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