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.