Re: agoodall Re: [OT] Double Messages

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

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.