title: Why does the Email trace listener prevent other listeners from working?
body: <p>We use Enterprise Library Application Block 6 to implement logging. We have two trace listeners, one for  logging to the database, another for sending email-alerts. They are configured like this:</p>
  
  <pre><code>&lt;loggingConfiguration name="Logging Application Block" tracingEnabled="true" defaultCategory="MyProject" logWarningsWhenNoCategoriesMatch="true"&gt;
      &lt;listeners&gt;
          &lt;add name="Database Trace Listener" type="Microsoft.Practices.EnterpriseLibrary.Logging.Database.FormattedDatabaseTraceListener,Microsoft.Practices.EnterpriseLibrary.Logging.Database" ... /&gt;
          &lt;add name="Email Trace Listener" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.EmailTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Version=5.0.414.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" ... /&gt;
      &lt;/listeners&gt;
      &lt;categorySources&gt;
          &lt;add switchValue="All" name="MyProject"&gt;
              &lt;listeners&gt;
                  &lt;add name="Email Trace Listener" /&gt;
                  &lt;add name="Database Trace Listener" /&gt;
              &lt;/listeners&gt;
          &lt;/add&gt;
      &lt;/categorySources&gt;
      ...
  &lt;/loggingConfiguration&gt;
  </code></pre>
  
  <p>Our problem is, that if the Email trace listener does't work for some reason - the SMTP server is down, for instance - then the Database Trace Listener doesn't work either.<br>
  Is there a way to configure the DB Trace Listener to work even if the Email tracing failed?</p>