On Tue, 4 Jul 2006, W B Hacker wrote: > > A situation where some but not all, lookups are recursively nested, and > potentially to different depths, may be supportable in the code. But > 'IMNSHO' represents an administrative, user-interface and user-education > load that need not be taken on when many-to-one flat mapping delivers > the same result with fewer machine resources and less risk of confusion.
That doesn't agree with my experience. Our virtual domain system typically handles personal aliases via a couple of redirections: see http://www.cam.ac.uk/cs/docs/eleaflets/g25/ These usually resolve to an @cam address which in turn usually resiolves to an @hermes address - though the user can change their @cam forwarding. A typical example is: [EMAIL PROTECTED] <-- [EMAIL PROTECTED] <-- [EMAIL PROTECTED] <-- [EMAIL PROTECTED] <-- [EMAIL PROTECTED] Our users often have addresses in three domains on our mail switch: one for their college affiliation (managed by the college's IT staff), one for their department affiliation (managed by the department's IT staff), and one @cam (controlled by the user). It's not actually possible to acheive one-step redirections across all those domains on a system where they are under administrative control by different people who don't work with each other - do you really want the user to have to bug several different IT staff to get their redirections changed? I suppose we could do so with a much more complicated database infrastructure, but why bother when Exim can resolve it at run time? The most likely cause of problems is if someone accidentally creates a loop, but since most redirections fan in to @cam before fanning out again (i.e. few redirections directly between subdomains), this is in practice very rare. (PS. I've sketched over the fact that users can independently control redirection of their @cam and @hermes addresses, which is indeed a bug because they have two ways to control the same functionality without any protections against getting in a mess. We avoid most of the problems because the @cam redirection is much more obscure than the @hermes redirection. The point is that you minimise support costs by minimising the number of ways of doing something.) Tony. -- <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> http://dotat.at/ ${sg{\N${sg{\ N\}{([^N]*)(.)(.)(.*)}{\$1\$3\$2\$1\$3\n\$2\$3\$4\$3\n\$3\$2\$4}}\ \N}{([^N]*)(.)(.)(.*)}{\$1\$3\$2\$1\$3\n\$2\$3\$4\$3\n\$3\$2\$4}} -- ## List details at http://www.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://www.exim.org/eximwiki/
