Depending on the email client (like Outlook, Gmail, Hotmail etc) and settings (Firewalls, security), the registration confirmation email might end up in the user's junk/spam mail or trapped by a corporate firewall and therefore undelivered.
As a Program Manager, you can activate a user's account for them:
- Go to Users
- Click on the Confirm link next to the status "Awaiting confirmation"
This will activate the user account and they can proceed to use their account.