FileMaker does a very good job of this straight out of the box. When you look at the Send Mail dialog box, you will see the ability to use a field value for the TO area. After you choose to use a field value, another dialog box will come up to allow you to choose which field. To send to a found set, you will need to build a loop in your script to go to each record and it will in turn send an individual email to each person. This gives you the desired one email, many addresses to receive it.
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