only alert on master

services/document-updater/Jenkinsfile

@@ -75,6 +75,10 @@ pipeline {
 
   post {
     failure {
+      when {
+        branch 'master'
+      }
+      
       mail(from: "${EMAIL_ALERT_FROM}",
            to: "${EMAIL_ALERT_TO}",
            subject: "Jenkins build failed: ${JOB_NAME}:${BUILD_NUMBER}",