I did some investigating today as to why so many new members have experienced trouble verifying their accounts. It turned out that a PHP update broke backward compatibility with some of the email code.
Good News:
I have fixed all the email code, so emails are now going out for all the features offered by the SDK Community.
Better News:
I have overhauled the methods of handling account verification and lost password retrieval. These are both more secure than beforehand. Also, account verification can now be reinitiated by the member at any time from within the Settings area. This will lessen the burden on admins of manually verifying accounts.