Outbound mail flow is not working
Have you ever had an outbound mail flow problem? Because most users rarely second guess whether the emails they send are delivered, it may take a while before this problem can be discovered. Then, by the time somebody reports this issue, the mail queues will already be severely clogged. Once the root cause is discovered, waiting for the queues to flush is required.
Notice how quickly Mailscape was able to identify that mail was backing up to your front end server and that your SMTP service was not operational. Mailscape can help you detect problems quickly and jump start your troubleshooting process.