How to add email notification in jenkins if the build is failed

reg. Email-ext plugin

In pipeline job you can use post build actions / try catch with proper step - ref. to mail

pipeline {    agent any    stages {        stage('Test') {            steps {                sh 'echo "Fail!"; exit 1'            }        }    }    post {        always {            echo 'This will always run'        }        success {            echo 'This will run only if successful'        }        failure {            echo 'This will run only if failed'        }        unstable {            echo 'This will run only if the run was marked as unstable'        }        changed {            echo 'This will run only if the state of the Pipeline has changed'            echo 'For example, if the Pipeline was previously failing but is now successful'        }    }}

or try-catch (scripted way)

try{//code to handle  } catch (e) {             emailext (            from: 'sender@domain.com',            to: 'recepient@domain.com',            subject: "job failed- ${env.JOB_NAME}, Build #${env.BUILD_NUMBER}, FAILED",            attachLog: true,body: """Foooooo text For current build refer to: ${env.BUILD_URL}job: ${env.JOB_NAME}build number: #${env.BUILD_NUMBER}With ERROR:${e.message}For full log refer to ${env.BUILD_URL}"""          )        throw e   }      

Post Build Actions > Email Notification

Part of the Mailer plugin.