Inviting existing user's email address gives error "Please enter a valid email address. " (BB-6049)
The email address is valid. I have tried this with more than one address. They do not contain any special characters; in fact when trying the same address but with the google trick of +something, it works. For example firstname.lastname@example.org is invalid (already registered actually), whereas email@example.com is valid.
The error message is incorrect.