Rule dispositionNotificationContent() { return Sequence( push(MDNReport.builder()), Optional(Sequence(reportingUaField(), ACTION(setReportingUaField()), crlf())), Optional(Sequence(mdnGatewayField(), ACTION(setMdnGatewayField()), crlf())), Optional(Sequence(originalRecipientField(), ACTION(setOriginalRecipientField()), crlf())), Sequence(finalRecipientField(), ACTION(setFinalRecipientField()), crlf()), Optional(Sequence(originalMessageIdField(), ACTION(setOriginalMessageIdField()), crlf())), Sequence(dispositionField(), ACTION(setDispositionField()), crlf()), ZeroOrMore(Sequence(errorField(), ACTION(addErrorField()), crlf())), ZeroOrMore(Sequence(extentionField(), ACTION(addExtensionField()), crlf())), ACTION(buildMDNReport())); }