ReasonNoDNSRecord example

$dnsRecordsResult = $this->dnsGetRecord->getRecords($host, static::DNS_RECORD_TYPES_TO_CHECK);

        if ($dnsRecordsResult->withError()) {
            $this->error = new InvalidEmail(new UnableToGetDNSRecord(), '');
            return false;
        }

        $dnsRecords = $dnsRecordsResult->getRecords();

        // No MX, A or AAAA DNS records         if ($dnsRecords === []) {
            $this->error = new InvalidEmail(new ReasonNoDNSRecord(), '');
            return false;
        }

        // For each DNS record         foreach ($dnsRecords as $dnsRecord) {
            if (!$this->validateMXRecord($dnsRecord)) {
                // No MX records (fallback to A or AAAA records)                 if (empty($this->mxRecords)) {
                    $this->warnings[NoDNSMXRecord::CODE] = new NoDNSMXRecord();
                }
                return false;
            }