Hi, >I'm not entirely sure what these RSETs are but they could be that the >customer was hammering our mail server and we ran out of smtpd >connections/processes to handle it.
RSET is an SMTP command sent by the client. Form what I see, your Postfix duely tried to reply to it but the reply dropped in a timeout. I am pretty sure that shows the client getting the hiccups while spamming. -nik