customized email

When someone checks out, if the product string matches a certain criteria I would like to send an email confirmation to an an additional email address showing the order.

Can someone tell me where I can insert this code in the files?

This is being used for my drop ship clients. I need to have the order emailed to the manufacturer, so they can ship everything out.

Thanks for the help.

Look in system/library/mail.php - just go right to the end of the file where the mail() function is called.
You can then check the $message for your 'pattern'

that makes sense. thank you.

Where can I change the content of an email?

Is this in a template file?

I would like to send 2 different formatted emails. One to the customer and store owner, and one to our drop ship client.

I believe the email sent when ordering is in the catalog/model/checkout/order.php file... (off the top of my head)... you should be able to add your extra mail requirements there.