[CentOS] Recommend Mail Server
christopher.chan at bradbury.edu.hk
Tue Nov 24 08:03:30 UTC 2009
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.
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