539031 Email Cron Script re-write

Need to take existing Cron file that sends out all of email Datatbase at same time And make it only send 500 out every 60 minutes , may require you to have File to only grab 500 lets say from 1-499 then another file grab 500 -999 and so on. Each cron file will be set to go off a a certain hour till it reaches the final amount at the end of the day. The cron for the website is already working, but it only sends out all of the data base in one shot, I need it to only send 500 every 60 minutes on the hour. so you need to i guess re-write the existing cron file to just send 500 every 60 minutes instead of all in one shot. I am looking for a Dedicated Programmer. You must have Past experience with this type of Cron. Please dont BS me, Either you can do it or you cant. There is no room for trying to do it, you must be confident in your work. I am ready to hire right now.