Re: [EXIM] parallel deliveries of big list on different mach…

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Author: Nigel Metheringham
Date:  
To: mark david mcCreary
CC: exim-users
Subject: Re: [EXIM] parallel deliveries of big list on different machines

mdm@??? said:
} I am interested in busting up the delivery of a big mailing list among
} several computers, each one on a different connection to the net, all
} running Exim, and am looking for some feedback on the various
} alternatives.

Ideally if you are splitting a list up in this fashion, then you would end
up with all deliveries that terminate on a single set of machines being
handled by the same distribution machine. In the old days the way to do
this was to split on the last component of the domain name - ie all uk
addresses went together, all com etc....
The world is now more complex and less regular (actually this never worked
very well but was good for a first approximation).
If I was trying to do this I would build a set of domain patterns and
distribution machines. This list would be built up by taking the current
list membership and analysing the routing of the addresses (this could be
done either by writing something to do the lookups, or maybe by analyzing
the logs of the mailing list distributors and working out where things go
to and grouping similar sets together. These groups are then distributed
across your distribution machines, also making allowances if one machine
is located so that it can see (say) UK interconnect points well.

You would end up with a domain lookup file seomthing like

    # the default if nothing else matches
    *            dist1
    # basic fallback for things we don't know/care about
    *.uk            dist1
    *.com            dist2
    *.net            dist3
    *.org            dist1
    # ... and more of these
    # specific rules
    # all planet based domains go together
    *.freeserve.co.uk    dist2
    *.theplanet.net        dist2
    *.theplanet.co.uk    dist2
    *.pla.net.uk        dist2
    # .. and another 100000000 planet domains
    # then for other groupings....


    # etc


This could then be used in a domainlist router (can you do partial
matchings in a domainlist) or a smarthost router (you can do anything with
a couple of lookups and a smarthost/smartuser).

The process you use to compute the distribution set groupings could be
rerun every so often (say monthly) to ensure that you still have a
reasonable balance.

    Nigel.
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