agoodall Re: [OT] Double Messages

I've gotten a few over the last few weeks, but I did notice that both the ones
today were from Allan.

Allan: You're only on the regular list, not digest, right?

The_Beast

> On Tue, 03 April 2001, devans@uneb.edu wrote:

> I've gotten a few over the last few weeks, but I did notice that both

Yep. Sorry, it's my canada.com account. It's doing weird things. I'm not
deliberately sending out double messages...

Allan (and anyone else bither by this),

No, its probably not your canada.com account. Its just a quirk of the way that
email messages are transmitted across the Internet. Occasionally message
packets will get routed teo (or more) different ways. When this happens,
because of the different delays in each route (goodness knows how many routers
and intermediate MTAs a message will pass thro) then the message ends up
getting duplicated. Its something we all just have to put up with. Happily it
does'nt happen too often.

Mike

> On Tue, 03 April 2001, devans@uneb.edu wrote:

> I've gotten a few over the last few weeks, but I did notice that both

Yep. Sorry, it's my canada.com account. It's doing weird things. I'm not
deliberately sending out double messages...

Allan Goodall - agoodall@canada.com
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Thank you.

On  4-Apr-01 at 06:43, Mike.Elliott@bull.co.uk (Mike.Elliott@bull.co.uk)
wrote:
> Allan (and anyone else bither by this),

Not to be a wet blanket, but packets _may_ be routed two ways, but
the whole message will end up on the server in one block. See, each TCP packet
has a sequence number, if you get two with the same
sequence number you throw one away.  If you are getting two e-mail
messages some machine has generated it twice.

In message <OF155FD122.AE95C2E0-ON80256A24.003A845A@bull.co.uk>,
Mike.Elliott@b
> ull.co.uk writes:

This is off-topic so I probably shouldn't, but I can't help myself.  I
don't believe this is correct. Or, rather, it's correct but shouldn't cause
duplicated messages.

SMTP is a TCP protocol, meaning each packet has a sequence number and the
sender receives an acknowledgement for each packet sequence number received.
It very well may be that a packet takes a different route, but packets that
arrive out of order are in essence ignored and forced to be resent until the
receiver receives everything once correctly.
This may make your e-mail slow, but it shouldn't cause two duplicate
messages.  Note that this keeps the e-mail flowing accurately even
when some packets are totally lost.

The most likely problem is a bug in somebody's mail server or client, or
perhaps even more likely, their mail server configuration.

Mike,

It happened to me seven times in one day. I did not go back and try to count
the others from the day before. I do not call that something I should just
deal with, that is a problem.

                Daniel

> -----Original Message-----