only alert on master failure

services/chat/Jenkinsfile

@@ -64,6 +64,10 @@ pipeline {
 
   post {
     failure {
+      when {
+        branch 'master'
+      }
+      
       mail(from: "${EMAIL_ALERT_FROM}",
            to: "${EMAIL_ALERT_TO}",
            subject: "Jenkins build failed: ${JOB_NAME}:${BUILD_NUMBER}",