Cannot speak of the internal workings of that specific add-on because I'm not familiar with that but few suggestions/questions out of the blue:
1. Have you checked your Spam folders in your mail?
2. Are you receiving other mails from concrete5?
3. Is it possible to contact your hosting provider and ask them whether they have changed anything regarding sending mails on that server?

But it's a shame if the add-on developers is not answering you because if the problem cannot be found from the server-side, it must be because of the add-on itself, maybe you recently updated it?

Thanks for getting back to me.

1. Yes Nothing in there
2. Yes all fine
3. tried that also

Hey Tim, I sent the developer an email about his lack of attention to support. Hopefully you will see a reply from him soon.

Working on it now. Sorry for the delay.

Oh, that's me above 'celwell'. When you get a chance, can you please respond to my reply in the Support ticket you started?

Thanks

The answer was to do with permission on the file see here
http://www.concrete5.org/marketplace/addons/forms-with-paypal-payme...