Subscriptions are not working

Hi guys,

Thanks for making this plugin.

everything seems to work on my site http://www.bitedge.co/ until I enter an email address and press subscribe then red text shows

“Please verify your email address.”

and

/?mailgun-message%5B0%5D=invalid-email&mailgun-error=338c3a116f4f53abbf8fa902f09106b8

is amended to the URL. I have tried uninstaling and reinstalling on 2 different sites, disabling all other plugins, entering multiple valid emails and nothing gets past it. I have 2 guesses as to what the problem might be.

1. this plugin
Requires: 3.9 or higher
Compatible up to: 3.9.8
Last Updated: 2014-7-31

but my site has the newest WP 4.2.4, I am happy to be a tester to get this working in the latest version of WP but I can not code.

2. I am not sure what if anything I am supposed to enter into the API Public Key field, I have tried leaving it blank, entering the API key and the API Base URL and there is no difference.

Thanks if you can help

https://ww.wp.xz.cn/plugins/mailgun-subscriptions/