Les Mikesell wrote:
Christopher Chan wrote:
You are removing a layer if you just pass through the recipient check to the ultimate source (the internal delivery machine) before accepting, and it does in fact need to be able to handle the lookups at the speed real messages come in. However, your external relay is likely to get whacked with a dictionary attack that it needs to be able to reject quickly so you can't do that if the delivery box is slow.
OH are we? So what happens when the frontend hands off to the internal delivery machine? Does not the internal delivery machine again do another lookup?
Yes, but it is pretty unlikely that the results will be different since they are both done quickly against the authoritative source. Unlike if you had made an intermediate copy of the database.
You can chain lookups. At least in postfix. So the results will be the same if you had a local copy in cdb format.