I am having problem where I get the following error message:

The following error occurred in FormMail :

Invalid email addresses were specified in the form :
recipients: edmtreg@gmail.com

he problem is that this is a valid address. I have also verified that it is a good, working address. I am listing couple of recipients so the form goes to multiple locations. The line is:
<input type="hidden" name="recipients" value="email1, email2, email3, email4" />

Is there a limit on the number of recipients that can be specified?

Thanks for any help you can provide.