From IThemes Codex
This section of the tools are meant to help with any troubleshooting emails.
- Email Queue- The queue will show if there are any emails that are currently queued up to be sent but haven't been sent yet. There are two buttons, "Force Send Queue Now" and "Clear Queue", that will allow you to manually control the queued emails.
- Send Test Message - This feature allows for sending a test email to any email address that you specify so that you can easily test if emailing is working correctly.
- Unsubscribe User from All Lists - Using this feature will unsubscribe a user from all groups and events.