Data Sheet Distribution

We need a piece of software that can look at Sage 50 to see what products customers have had and then send an email to them with the relevant data sheets for that product.

However, we do not want to send the same datasheet twice so if they have already had the proudct and had the datasheet then we don't want to send it again. Furthermore if they have had the product and datasheet before but the datasheet has been updated in the meantime we want to send them the revised version next time they order that product.

I have added a budget but wasn't really sure where to start with this.