On Mon, 9 Jul 2007, Marc Perkel wrote:
> The idea behind this is that it requires the server be touched twice in
> the proper order to get in. Spam bots try once and not in the proper
> order. That's how the filter works.
Presumably you have some kind of white listing? Otherwise, Exim as a
sender will behave like this:
1. Try first IP
2. Temporary error - remember this
3. Try next IP
4. Accepted - message delivered
5. New message arrives
6. First IP hasn't reached its retry time yet
7. Try second IP
Will that be accepted?
If so, that's fine for a server sending from a single IP. What about a
server that sends from different IPs (because it's implementing a number
of virtual servers) but has a single set of retry data? In the above
scenario, the second message could then be from a different IP. (There
are servers that do this - facilities were added to Exim not very long
ago to make it easy to do this.)
--
Philip Hazel University of Cambridge Computing Service
Get the Exim 4 book: http://www.uit.co.uk/exim-book
