"Rodney Broom" <[EMAIL PROTECTED]> writes:
> ===> OK, to be fair I'll include the example of sending a bunch of mail to
> this same domain with a single connection but with differing message bodies.
Note that VERP, which is very useful for mailing lists, requires this
approach, because the one connection approach doesn't permit a
different envelope sender for each recipient.
> - Lookup recipient domain.
> This requires getting the current MX for the recipient.
> - Open a socket to the mail server for the recipient domain (connect).
> - Tell the recipient mail server who you are. (trivial, but existant)
> - For each message:
> * Send the mail (headers and body)
> - Close the socket connection.
>
> See, we've missed 5000 name lookups and socket connections. I'll admit that
> a decent name server helps this. Also, that creating a socket isn't very
> expensive on today's hardware, but it's at least a little bit of the load.
> What will become expensive is establishing the actuall connection with the
> remote machine (which happens after the socket is created and before data is
> sent).
You have correctly demonstrated that an approach other than the qmail
uses will reduce the number of bytes sent over the network. If you
pay for your network usage by the byte, then this could be important.
For people with a flat rate connection, however, minimizing message
delivery latency is usually more interesting. qmail sends many
messages in parallel, which helps to overcome the round trip latency
inherent in the SMTP protocol. Overall, the messages will be
delivered faster using qmail.
This has all been discussed in the archives before. I encourage you
to check them.
Ian
