Aaron S. Joyner
aaron at joyner.ws
Thu Dec 16 11:15:52 EST 2004
Rick DeNatale wrote:
>For those of us who use things like gmail, which no doubt use email
>server farms, it might take a while for all of those ip addresses to
>In other words the "you" in "the first time you send a message to the
>list." is a bit fuzzy in these cases.
>At least it looks like the mail will get a soft bounce, and not a hard bounce.
Intelligent mail systems (like Gmail, presumably) will send your message
to one of a dozen or more "outgoing" smtp relays. That message then
gets queued up on that machine for delivery, and that one machine is
responsible for the final delivery of that message. Each delivery
attempt will come from that one machine, with it's IP address. This is
by far the easiest way to scale this solution, as it only requires a lot
of boxes, and one round-robin DNS entry.
Less intelligent systems may do as you fear, and have one large queue,
and any of a dozen machines can pull out the message and send it. Not
only is this method more difficult to implement, it's much messier and
has a central point of failure (that big central queue). As the
popularity of greylisting spreads, people will stop doing brain-dead
things like that. :) Most of them already have. In the very unlikely
case that turns out to be a problem, we have the flexibility to add
exceptions to the grey-listing, based on IP address or IP address range,
which allows us to work around the stupidity of others.
Aaron S. Joyner
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