using mailboxes.db replicated copy for lmtpdproxyd

[Rob Siemborski]

On Mon, 2 Feb 2004, Andrey B Semakin wrote:

> Is it possible for lmtpdproxyd to use mailboxes.db local replicated copy
> (as for proxyd) instead of using mupdate master server directly?

Not currently, though you could configure it to look at the local mupdate
instance.

Note that doing this has a cost: mailbox data on any replica can be out of
date.  So, you now have a race condition.

Imagine you try to deliver a message to a user on a backend (a) at the
same time that the mailbox is moving from (a) to (b).  If the lookup that
happens in the replica says that the mailbox is on (a), but the mailbox is
*actually* on (b), but then delivery is attempted on (a), the mail will
bounce (permanant failure).

Note that for reasons of our own we'll probably be looking at making some
form of geographicly distributed mupdate replicas more palateable, though
I doubt we could fix this issue completely given the current architechure.

-Rob

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Rob Siemborski * Andrew Systems Group * Cyert Hall 207 * 412-268-7456
Research Systems Programmer * /usr/contributed Gatekeeper