Christopher Chan wrote:
Ian pointed how he needs to 'replicate' a local copy of user 'accounts' from Exchange so that he does not kill Exchange. I just pointed out that this sort of thing can be done also for sites with a very large user base that will want something that is more efficient that Berkeley DB.
There might be a few places big enough where using cdb vs. the built in bdb for the virtuser table would matter. But very few.
You can chain lookups in postfix. Check cdb, then check mysql/postgresql. If the account exists in the cdb, then there is no need to check mysql/postgresql. So essentially only non-existent addresses and recently created addresses will result in hits to mysql/postgresql. This is not a work around. This is performance enhancement. Whacking a local cdb will be faster than whacking a mysql/postgresql database. Geez.
If you have a reasonably fast internal mailer you can just let mimedefang on your external relay check against it with smtp in real time. Exchange isn't one of those, though.