"&emailTo" to multiple end-user entered email addresses

I think I am making this harder than it is, but I can't figure it out. I have a form where the end-user will enter the address to send the email to, so the value of that field is "[[!+fi.friends-email]]".

It works great, but I need to be able to allow the end-user to submit multiple addresses in that field. I thought I would just be able to enter in a few addresses with commas, but it didn't work.

Any suggestions??