More information from my support request with siteGround is as follows:
SiteGround States: "Indeed this is why I have asked you to let us know where are the settings, since the Joomla's Global Configuration settings work properly with the Joomla's Contact Us form and mass mail function, they should work with the Community Builder component if everything is normal with the component itself.
I have also tried to register and see is the e-mail message is delivered, however, after the registration I have checked our server e-mail logs and did not to find any sent messages. This means that the component itself is not even trying to send the messages using the server.
What I can recommend you in this case is to keep monitoring the thread that you have provided us with in your last message and wait for reply in it, since the issue is most probably due to the fact that something is not set up properly in the component."
SiteGround states it is a problem with the CB component. So . . . can you please shed some light on this?
Thanks!
Emily