[Mailman-Developers] Huge lists

J C Lawrence claw@kanga.nu
Wed, 24 May 2000 15:41:38 -0700

On Wed, 24 May 2000 15:52:52 +0100 
Nigel Metheringham <Nigel.Metheringham@VData.co.uk> wrote:

> claw@kanga.nu said:
>> Actually on the input side it would be 2M/SMTP_MAX_RCPTS where
>> SMTP_MAX_RCPTS defaults to 500.  Additionally, Exim (I haven't
>> checked Postfix, but I doubt it) does not collapse identical
>> spool entries with different RCPT TO lists, so you're still left
>> with the same number (checking for identicallity is expensive).

> You pedant :-)

Why, yes! 

> Granted although that raises the other issue... Barry mentioned
> yesterday that he was putting the dropped SMTP_MAX_RCPTS
> functionality back in... but I thought it had deliberately gone on
> the basis that mailman was giving the mail delivery job to the MTA
> and not trying to second guess it.

SMTP_MAX_RCPTS needs to be there as some MTAs have internal limits
on the number of RCPT TOs.  It used to be the old BitNet and big
iron machines that were most known for this.  Don't know wha't out
there now, tho I remember getting a couple bounces for that reason a
couple years back.

> If we do split the list, then ideally it should be sorted.... at
> least so identical domains go together and maybe more
> intelligently than that.... and we're back to trying to second
> guess the MTA at its own job.

Sorting the RCPT TO list by domain costs us very little (esp if we
sort on insertion), and can help users of dumb MTAs considerably.
Its seems a *reasonable* tradeoff, tho argument could also be made
that it merely supports the continued use of broken software -- but
I'll leave that argument for another time.

Yep, its second guessing the MTA, but its a cheap, cost effective,
minimal impact guess that has nearly NO punitive effect on mailman

>> I would expect them to have configured their MTA to not attempt
>> pre-lookups for messages arriving from MailMan.

> I guess that we need a per MTA tuning/configuration document.  

Aaaargh.  Yes.

> I pretty much have that in the exim mailman howto...

BTW, well done on the Exim HOW-TO.  Nicely done.

> (always willing to take contributions/comments on that BTW -
> especially if they suggest solutions rather than just raising
> criticisms).

Without going and re-reading it, about the only thing I can think to
add to it would be turning off domain checking for localhost RCPTs
as per our recent comments if that's not there already.

BTW: Does Exim index its spool on the basis of MX?  It doesn't
*look* like it per watching it, but I haven't checked.

How about Postfix?  Anybody know?

> Have we got that data for the other MTAs?  

Nope.  User written of course, and well, you know.

> Of course we could have comparisons of the suitabilities of
> different MTAs if people enjoy a decent flamefest.

Of course not.  Everybody knows that Microsoft Exchange is the one
true MTA and all else are but pale imitations.

J C Lawrence                                 Home: claw@kanga.nu
----------(*)                              Other: coder@kanga.nu
--=| A man is as sane as he is dangerous to his environment |=--