vvrpgsporcupineorg wietse venema barak yakir thanks reply please let rephrase problem talked isp policy follow 1 12 tcp connection per minute result 5 minutes ban etcpostfixmaincf requires postfix 25 later smtp_destination_rate_delay 10s unfortunately per destination per smtp transport wietse 2 250 recipients per message result discarding entire message default setting default_destination_recipient_limit 50 wietse given time might 12 different domains deliver hosted behind isp mx host constructing transport table hosted domain nightmare talking hundreds domains limit number connections mx host well number recipients per message avoid breaking policy thanks barak yakir victor duchovni wrote mon feb 11 2008 084736am 0500 wietse venema wrote barak yakir hi im trying set postfx 2322 cache destination network address one major isps primary mx record host hundreds domains im using smtp_connection_cache_destinations foocom working forcing set list new domain every time im getting error mail server perhaps really trying limit concurrency isp connection caching alone wont dramatically reduce concurrency demand postfix queue manager groupsschedules messages destination domain mx host unless construct table domains resolve isps mx host table good built time used route mail question transport suitable process limit cant solve suspect real problem tue 05 aug 2008 211251 0500 smtp_connection_cache_destinations network address