vl dhhznxfaegmailcom yes always install least two postfix instances mail servers default instance etcpostfix vanilla nullclient handles local submission relays everything via smtp internal msa real mta always second instance sometimes configured cluster configuration failover actually bit interesting since machine pair runs native listener instance twin failed drainonly queue twin anyway fully automated set spend time right works tm easy support find multiple singlefunction simple instances large scale environments easier manage monolithic kitchen sink point documentation running 2 postfix instances one machine understand create 2nd postfix configuration directory change path spool directories execute via postfix c otherdir right wed 06 aug 2008 053647 0300 local delivery cluster enviroment