Our organization has been sending out weekly newsletters to our paying subscribers for a year and a half with hostmysite. Each newsletter ranges between 1,500 and 2,500 emails. Recently we have encountered problems with sending too much email too quickly to your mail servers. Half of them wont go out and errors are generated stating that "Remote host said: 554 : Sender address rejected: too many emails from this sender( 2 )". My question is what settings should we use for our internal Coldfusion server that will allow our emails to be sent in a timetable that is compatible with your servers. The two settings I have configured are:

Spooling Interval: 60 Sec.
Simultaneous Threads: 3

Should I slow these down even further?