victor duchovni dxdewmdieulnutmorganstanleycom wed feb 13 2008 053234pm 0500 vivek khera wrote feb 13 2008 250 pm victor duchovni wrote yes 25 adds support perdestination rate limits really intended users soho isp msas fact major isp inbound mx host rather sad list dozen remote sites isps universities nonprofits throttle delivery im keen implementing 25 proper rate limits rather faking concurrency limits isps actually need low concurrency limits rather rate limits also pita one things looking able test 25 new selftuning concurrency feedback controls described part scheduler_readme specifically isp gives immediate 421 banner ehlohelo negative feedback concurrency overshoot make sticky subsequent blackout time new connections postfix 25 converge isps limits right feedback settings convergence means postfix mostly operate maximum allowed concurrency periodically try one connection fraction mail may deferred fraction much lower prior releases interesting parameter values smtp_destination_concurrency_negative_feedback 120 smtp_destination_concurrency_positive_feedback 18 exhibit defer rate 10 less destinations preferred concurrency limit smtp_destination_concurrency_limit get lower defer rate less 115 messages smtp_destination_concurrency_negative_feedback 120 smtp_destination_concurrency_positive_feedback 115 may result low concurrency site behind single loadbalanced ip 50 connection failure rate doubt sites real problem algorithms lead slightly slower concurrency growth cold start likely fine interested performance comparisons viktor disclaimer offlist followups get onlist replies get ignored please ignore replyto header unsubscribe postfixusers list visit httpwwwpostfixorglistshtml click link response solves problem best way thank send worked thanks followup must respond please put worked thanks subject delete quickly tue 05 aug 2008 190759 0500 comcasts 6 recipient per second limit