Brian,
Regarding Sendy, can you let us know what's not working? Any details of the issue would help us narrow down the cause and provide a solution.
As for the issue with Google, that's not one we've heard of before. HTTP/2 protocol is a default capability on many servers now, but it's possible there's a configuration issue on yours that's causing problems. An easy way to likely fix this is by telling cURL (the PHP functionality that makes requests to other websites) to use the older protocol version.
To do that, please edit the following file:
/components/com_jfbconnect/libraries/joomla/http/transport/curl.php
Around line 44, you'll see:
After that line, add the following:
$options[CURLOPT_HTTP_VERSION] = CURL_HTTP_VERSION_1_1;
That will affect all requests made by JFBConnect, but will not change any other functionality within Joomla.
Please test that and let us know how it goes. If it fixes it for you, we can investigate adding an option in JFBConnect for compatibility with that setting in the future.
Thanks!
Alex