Autoreply script- timed automatic email reply program

AutoREPLY from email broadcast. This should be an easy job for someone with the right set of skills. Heres's what I would like to do and I'm not sure if I have to set up a cron job at the host or have something set at the email client. I think I'm going to use squirrelmail as the email client. I could use google apps if there is a way to get around the 500 emails per hour cap. I will be using an autoreponder service like autoresponse plus, ListmailPro or [login to view URL] whichever will be able to integrate this kind of programming. I would like to send an email broadcast to a list of say 3,000 that I upload to the autoresponder from a csv file. Say I get 200 replies that go to my email client. I would like those 200 replies I got to get an automated reply back 24 hours later. If they reply to my reply they cannot get that same automated reply they must be separated so I can respond to them "manually". I'm thinking maybe a filter that automatically replies to all new emails and adds these new email addresses to the contacts folder. Then all emails that come in get filtered for duplicates against the contacts. If they are already a contact they go to another folder and DO NOT get an automated reply. If they are not a contact they get an automated reply (24 hours later) and they get added to the contacts so they don't get another automatic response if they reply back to my "manual" reply. Hope this makes sense. Any and all ideas are welcome. thx,