I have been trying that recently I cannot receive a confirmation email after registration of my website.I was using PHP mail now changed to senmail I had the same problem. Ay suggestion. A user can send email from website to web admin.
JFBConnect doesn't control how the email is sent. We use whatever option is set in your Joomla -> Global Configuration area to send welcome emails and that usually relies on the underlying User component that comes with Joomla.
I'd recommend contacting your server provider or technical support to make sure you're using the proper mail credentials. Unfortunately, I don't know much more about that level of configuration in Joomla because it's not directly related to JFBConnect. I hope the above helps though.