Can't email invoices... Says please enter a valid email address??? (it's already there)

I have the same problem and reported it but still didn't get any reply.

I have the same problem as well

Hi - is this on the email view when sending an invoice or when adding an email address to a contact/organisation? Also, are all email addresses verifyed as working - you can check this on the site below:

http://verify-email.org/