further to above tarpitting has strengths activated on internet facing exchange hosts and generally is therefore applied on external internet incoming connectors, if you have a separate internal connector or edge you can consider turning tarpit off that
if need to check current setting on connector
Get-ReceiveConnector "connectorname" | select tarpitinterval
if need to disable tarpit on connector
Set-ReceiveConnector "connectorname" –TarpitInterval 00:00:00