mail and they catch you, they will almost certainly list you (since many people who run open relays for some odd reason think that they shouldn't be listed in databases of open relays). If you block them, they can't see whether or not you are an open relay.
We have a filter in IMGate that un-RFC hangs up on any SMTP client that commits more that "x" 5xx errors in one SMTP session. I set "x" to 2 and don't have any problems. It is an the best tarpitting defense. Minimum impact on us, and maximum impact on them, As Good As It Gets, Jack.
I suppose it could happen that when ordb sends 17 relay attempts in one SMTP session. IMGate 5xx's to every one, and after the 3rd one, IMGate hangs up on them. Then they could list us falsely as open relay. No problem so far, although I dimly remember it causing a problem last year.
But I refuse to run with ( "x" = 20 ) all the time on the very outside chance, twice/year?, that ordb might come visiting with their 17 tests. They should get smart and make 17 different SMTP connections instead of one.
Len
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