To configure BIT so that in case of failure it sends out the message to the specified address following should be done:

1. Locate Logging.config in 'Config' folder of BIT.
2. Add new Listener to the <listeners> section as shown below
<add name="Email Trace Listener" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.EmailTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
listenerDataType="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.EmailTraceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
toAddress="user1@example.com;user2@example.com" fromAddress="user3@example.com" subjectLineStarter="Exception Occured" subjectLineEnder="2" smtpServer="relay.domain.com" smtpPort="25"
formatter="Text Formatter" authenticationMode="UserNameAndPassword" useSSL="false" userName="anonymous"/>

Note:
Email settings from the ShareKnowledge system properties could be used for the configuration.

3. Add name "Email Trace Listener" to the event category as shown below

<add switchValue="All" name="Error">
<listeners>
<add name="ConsoleTraceListener"/>
<add name="FileTraceListener"/>
<add name="Email Trace Listener"/>
</listeners>
</add>

p.s.
Properties of the EmailListener class