[Mailman-Users] How many messages in an envelope?

[J C Lawrence]

On Tue, 24 Apr 2001 20:20:35 -0700 (PDT) 
alex wetmore <alex at phred.org> wrote:

> On Tue, 24 Apr 2001, J C Lawrence wrote:

>> Codswhallop.  Intelligent MTAs upon successfully connecting to an
>> MX will fork multiple queue runners to that target attempting to
>> deliver N parallel streams to the MX until the queue for that MX
>> is dry.  Even sendmail (finally) does this.

> Yes, but if there are many recipients on the one message then
> there is no reason to send many parallel streams to the final
> server.  

True.  This assumes that your MX distribution is very globby (ie
your have very large numbers of messages all being delivered to the
same domain).  In the general case this is true for AOL, Hotmail,
Yahoo, MSN, and a couple other domains, with the rest of the target
space being forms of large numbers of very small populations.  Once
you get past the point of those large globs being delivered you're
back to lock contention and reduced parallelism as each spool entry
now represents an increasingly large distribution of target MXes.

  Note: This happens to not be true for me. AOL+MSN+HotMail+Yahoo
  form less than 5% of my subscriber base.  

> The system can send one stream with all of the recipients, rather
> then many identical streams with a couple of recipients each.

Which is not necessarily faster, and in AOL's case in particular
will tend to cause AOL to silently delete your messages as suspected
SPAM without every delivering them to the recipients.

There are three variables here: NumberOfTransactions, Parallelism,
and Bandwidth.  The three of them rest on two variables:
TotalNumberOfRecipients and MessageSize.  Where the sweet spot on
that graph is for you is very dependant on your load, setup, etc as
previously discussed.

> It also depends on strongly on which MTA you are using.  

Yup, massively.

> I am very familiar with the Windows 2000 SMTP Server, and not as
> familiar with sendmail or postfix (I've used them for many years,
> but I haven't dug into them).

I can't comment on the Windows side of things, or SMTP Server's
spool handling/locking characteristics as I've never looked at or
used it.  I'm only passingly familiar with Sendmail (last used it in
any heat over 6 years ago).  Since then I've been using primarily
Exim, and more recently Postfix.  I don't feel that I have a full
grap on Postfix'es queue handling yet.

-- 
J C Lawrence                                       claw at kanga.nu
---------(*)                          http://www.kanga.nu/~claw/
--=| A man is as sane as he is dangerous to his environment |=--