You can use Attach task to this log or simply create a new scheduled task.
Use the trigger When a specific event is logged Choose the log you want to monitor (you can choose multiple logs in the advanced task settings)
Set the action to Send an e-mail (and provide the nescessary information)
If you want any error sending a message you have to refine the trigger. Edit the trigger and choose custom. Then you have to press the button new event filter...
Tick Error in the error level part
In the drop down menu by log you can choose the log you want to monitor
With this event filter you get a message for each error that occurs.