Simple Mac / Automator Script

Each day I get 30-40 new contacts. I need to send them a welcome message, and each message is a little bit different. I have it all down so that I have a spreadsheet with the following 5 columns: Name Email Address Email Subject CC Email Address Message Body I'm looking to have a quick script made with Automator where I can select the spreadsheet and hit go - the messages will all get composed in Apple Mail automatically, each message will be separate, addressed to each individual person, each will have their own unique subject and message body which is all getting pull from the spreadsheet. No I don't want Apple Mail to send all of these at once and slaughter my mail server, so I need some sort of solution that'll send these on a delay, something like one email every five minutes. Maybe that is a matter of something in my spreadsheet, I can have a date and time field, and the message will get sent on the date and time that is specified for each row. Or maybe there's a setting within Apple Mail to limit only one email being sent per five minutes, and the rest will just basically sit in the outbox being sent one by one every five minutes. I'd like this all to run on the same machine I am using, so I would like to avoid every five minutes having Automator pop open my email while I'm working on my computer. Something that's going to run in the background is ideal. Something to wear when I set it up and hit go, the emails will get created and start sending every five minutes without interrupting. Not sure if this is possible but I thought I'd throw this out there to see what could be done. Thanks!