[WWI] Not complaining....but

Allan Wright aew at unh.edu
Thu Aug 19 09:10:42 EDT 2004

Agreed, the true 'pixie magic' is that ANY mail arrives.

On Wed, 2004-08-18 at 16:39, Shane Weier wrote:
> Neil says
> >Don is correct, even for us who are in mail mode (not digest),
> >mails often arrive in the wrong order. It's pixie magic.
> >
> Back when I had a day job, I was responsible for email performance for my 
> global employers, so I have a reasonable understanding of what's happening. 
> Simplified slightly because I don't want to be more than usually boring this 
> is what happens...
> When you send an email, it goes from your PC to a mail server at your 
> service provider (ISP). To get to the destination it has to be passed 
> through a chain of mailservers, some (maybe) belonging to the same ISP, 
> mostly not. It's designed to be pretty bombproof, so if the data 
> communications between any of the servers is down for some reason the email 
> will be held and the server keeps trying until it gets through.
> But...if the line is down for a while one of several mechanisms can cause 
> your email to arrive out of order.
> If it's stored as it arrives (like stacking plates) and then sent by taking 
> the last arrived email and sending it on, then the next to last (like 
> unstacking plates) all the emails that were held will be sent in reverse 
> order.
> Or, the delayed mail can be reroutedby a slower path. If the original fast 
> link comes back up again the next (later) emails will go the fast route and 
> get to you first.
> or, even when things are working properly, where there are multiple paths, 
> some emails will go the fast way, others will go the slow way and arrive out 
> of order.
> But the should all arrive, and usually do, to an order of reliability which 
> in the context of the billions of emails flowing around is amazing even to 
> someone who spent his life working on data comms
> Shane
> .---- - --- ....- ---.. .-. ..- .-.. . ... .-.-.-
> My Strine is a Toad in Disguise
> .---- - --- ....- ---.. .-. ..- .-.. . ... .-.-.-
> _________________________________________________________________
> 10,000 children need sponsors  change a life:  
> http://ad.au.doubleclick.net/clk;9294008;9739733;y?http://www.worldvision.com.au/childsponsorship/search/child_search.asp?om=1

More information about the WWI mailing list