Adobe Acrobat form submit button error "One of the specified recipients is not resolvable" when I test the form online and hover over the button I don;t grt the finger pointer. How can I fix this?

Regarding the  "One of the specified recipients is not resolvable" error message: Make sure that there are no spaces in your mailto string, not after the colon, not in the email address, or anywhere else.

If it’s still happening you will need to share the actual string you’re using, or better yet, the actual file, for further help.

These are two different issues, neither of which appear to be issues related to Acrobat. 

First, Acrobat does not send emails directly, it does it by handing it off to either the local client or  a remote server.  So, if the form is open in Acrobat/Reader on the desktop, then the first thing that should happen when the button is pushed is a dialog is displayed asking the user how they want to send the email. Any messages about an email not being resolvable are displayed by the target email application. 

Second, if the form is opened in a browser or mobile device, then it is probably not open in Acrobat. So it’s not going to behave  the same way it would in the desktop Acrobat. Unfortunate, but correct behavior is only guaranteed in the targeted application.