At 10:22 AM -0500 2001/1/31, Wietse Venema wrote:

> In particular, each SMTP client does its own DNS lookups.

        Of course.

> These
> will presumably be cached by a local name server.

        Hopefully, yes.

> Will all SMTP
> clients see the same sequence of MX records? In that case, Postfix
> should shuffle the data.

        This would depend on the implementation of the local caching
nameserver. If it's implemented properly, I would expect it to
continue properly rotating the records according to their weight,
etc.... However, it may not be implemented properly, and in that
case each client would probably see the same sequence of records.

        Since I think we can safely assume that the "average" site would
probably be a fairly small one, and where the admin may not be
particularly knowledgeable, my inclination would be to make this an
option that can be changed, but default to have postfix do its own
randomization internally.

> Postfix obviously can't group recipients of different queue files
> into one delivery, but it can group up to 50 recipients of the same
> queue file into one delivery, and it can group deliveries by domain
> so that it can enforce its per-domain concurrency policy.

        Understood.

        I guess what I'm advocating is a combination of a hard and a soft
maximum number of recipients per delivery, and to have postfix
(qmgr?) try to find "natural" boundaries when splitting the envelope
into multiple queue files, such as all addresses within a particular
domain or subdomain, while also trying to minimize the total number
of queue files that will be created.

        Only if you have a number of recipients for a particular
domain/subdomain that is greater than the hard limit would you then
split this group into more than one queue file. In essence, this
becomes a "best fill" issue, such as using "fmt" or "par" to format
the text of all messages before you actually send them out via e-mail.

        Moreover, while I would promote recipients further down the list
to the same level as the first recipient within that same
domain/subdomain name, I wouldn't actually sort the list of
recipients by domain/subdomain name.

        This would allow for a reasonable maximum number of recipients to
be handled in a reasonable minimum number of deliveries, without
destroying too much of the information that might be encoded by the
sending program in the order it chooses for generating recipients.

--
   These are my opinions -- not to be taken as official Skynet policy
======================================================================
Brad Knowles, <brad.knowlesskynet.be>

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