I'm currently working on a Managed File Transfer (MFT) proof-of-concept for a client using Mule ESB Enterprise.  One of the requirements I had to address is the ability to send SMTP email messages when a particular connector failed, i.e. SFTP connection failed.  I thought to myself, that's a reasonable request and something that is probably straightforward to do in Mule ESB.  Well, if you look at the Mule configuration it is straightforward however, getting to that point using Gmail took some work...so I thought I'd share :)

What you need...

• Mule ESB (I'm using Mule ESB Enterprise Version: 2.2.5 Build: 16813 along with Mule Management Console support, i.e. mmc-agent-2.2.5.jar) *
• A test Gmail account

<?xml version="1.0"?>
<mule xmlns="http://www.mulesource.org/schema/mule/core/2.2"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:file="http://www.mulesource.org/schema/mule/file/2.2"
  xmlns:smtp="http://www.mulesource.org/schema/mule/smtp/2.2"
  xmlns:email="http://www.mulesource.org/schema/mule/email/2.2"
  xsi:schemaLocation="http://www.mulesource.org/schema/mule/core/2.2
    http://www.mulesource.org/schema/mule/core/2.2/mule.xsd
    http://www.mulesource.org/schema/mule/file/2.2
    http://www.mulesource.org/schema/mule/file/2.2/mule-file.xsd
    http://www.mulesource.org/schema/mule/smtp/2.2
    http://www.mulesource.org/schema/mule/smtp/2.2/mule-smtp.xsd
    http://www.mulesource.org/schema/mule/email/2.2 
    http://www.mulesource.org/schema/mule/email/2.2/mule-email.xsd">

  <description>Test configuration to send SMTP email through Gmail.</description>

  <!-- Configure some properties to work with GMail's SMTP -->
  <smtp:gmail-connector name="emailConnector" />

  <model name="processInboundFileModel">
    <service name="processInboundFileService">
      <inbound>
        <file:inbound-endpoint
                 path="./remoteFS">
        </file:inbound-endpoint>
      </inbound>
    
      <echo-component/>
    
      <outbound>
        <pass-through-router>
          <smtp:outbound-endpoint
            connector-ref="emailConnector"
            host="smtp.gmail.com"
            port="587"
            user="<account name>%40gmail.com"
            password="<password>"
            to="<email addresses>"
            from="<account name>@gmail.com"
            subject="Test email message"/>
        </pass-through-router>
      </outbound>
    </service>
  </model>
</mule>

From http://soatechlab.blogspot.com/2010/07/sending-outbound-smtp-messages-through.html