Job execution Failure

JobExecutionFailure: jobId:106671; ErrorMessage: java.util.concurrent.ExecutionException: com.adventnet.servicedesk.ServiceDeskException: Mail sending failed.; JobInfoObject: {"jobId":[106671],"moduleName":["MAIL_NOTIFICATION_JOB"],"executorClass":["com.manageengine.servicedesk.jobexecutors.MailNotificationJobExecutor"],"jobInput":["{\\\"ENTITY_NAME\\\":\\\"WORKORDER\\\",\\\"ENTITY_ID\\\":6243,\\\"NOTIFY_TYPE\\\":\\\"UnpickedQueueReqTechNotify_E-Mail\\\",\\\"NOTIFY_FROM\\\":\\\"QUEUEUTIL\\\"}"],"jobInputObjectStore":["com.manageengine.jobscheduler.JobInputObjectStore@2f537f63"],"errorInfo":[null]}