[unisog] When you really need to blast email

scott hollatz shollatz at d.umn.edu
Thu Mar 13 21:48:29 GMT 2008

> Michael Holstein [michael.holstein at csuohio.edu] asks
>> Our safety folks are working a campus-wide "emergency notice" system,
>> where one option will be email (the logic behind that is outside the
>> scope of this technical question).
> We do mass mailings to ~20+K for student e-voting (invitations to vote which
> are not personalized -- same message to everyone) where students are
> scattered about on different servers probably very much like yours. The
> practice has been to take the list (alpha sorted, not sorted by hostname),
> chunk that into shorter lists of 100 and blast those out. I.e. 200 messages
> each with 100 recips rather an 1 message with 20,000 recips.

The chunking and parallelized delivery is a big win.  Last spring we wrote
a program called 'blastmail' to send a lot of messages fast.

blastmail takes a list of recipients then does the splitting and sets up
parallel delivery.  The benchmark was to get 12+K recipients as fast
as possible.  One test did it in 22 seconds but the default configuration
delivers 12+K recipients in less than 1.5 minutes.

> To date we've not had the problem you describe. And yes we have lots of
> folks on hotmail, etc. The sending (modest Unix server) usually takes about
> 10mins with most delivered PDQ. The mail queue cleared within 30mins. No you
> don't get to everyone, but you get to hit a lot PDQ and that's probably
> enough for the "emergency notice".
> If you take a single message to ~20+K users you're going to end up with very
> long lists to popular mail servers who will, rightly, detect your mail as
> spam and may well black list your site. Chunking helps for us ... so far.

scott hollatz                                        net shollatz at d.UMn.eDu
information technology systems and services          tel +1 218 726 8851
university of minnesota duluth mn usa                fax +1 218 726 7674
                                               "Asn aD ta zlAp em uT zt33rg"

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