I suspect there is some sort of SMTP specific error message in your server.log file referring to its inability to send alert emails. This problem is most common when the SMTP default setting of using the localhost is an incorrect or invalid value for your environment.
You can specify an alternate SMTP host by editing the server.mail.host value in conf/hq-server.conf. If the SMTP server you are using requires authentication to send messages from a remote host, you will also need to edit the conf/templates/jboss-service-events.xml file, adding the SMTP user and password values under the existing SMTP values like so:
<property name="mail.smtp.user" value="firstname.lastname@example.org"/>
<property name="mail.smtp.password" value="YOURPASSWORD"/>
<property name="mail.smtp.auth" value="true"/>
After making the required changes, you will need to restart the HQ server. Following the restart, alert messages should be sent using the SMTP values you specified.