On Sun 24/Feb/2013 03:22:47 +0100 Ned Freed wrote:
Actually that is an interesting idea. The backup MX could act as an SMTP
proxy as long as it can maintain a connection with the primary. That
would also sort out your observation on address checking.
And when it can't it needs to be prepared to pass as much of the context of
the
original connection to the primary as possible later when the primary
becomes
available again. The IP address is especially important here, of course.
Again, it would be quite helpful if there was a standard for doing this.
Postfix has XCLIENT, we have something called XPEHLO, and there are
probably others out there.
Do those systems provide for keeping recipient lists in sync?
That's a totally separate problem. And yes, it is a problem, and there
are various ways to solve it, and it maybe makes sense to standardize one of
them. Or not - it's a fundamentally harder problem to solve, with a lot
more variabless.
It is
too easy to abuse of a backup forced to accept any recipient. OTOH, a
backup could stay disconnected from the primary for quite some time,
possibly transmitting mail to yet another backup which is able to
connect to the primary. So it may make sense to have a copy of the
mailbox names at the backup MX. What are the alternatives?
Again, you're talking about a different problem. Let's please focus on the
problem at hand, which is the transfer context from a secondary to a primary.
Divide and conquer.
Ned
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