hMailServer.Dns.DnsClient.ResolveMxHostNamesAsync C# (CSharp) Méthode

        private async Task<List<string>> ResolveMxHostNamesAsync(string domainName)
        {
            var dnsMessage = await _dnsClient.ResolveAsync(DomainName.Parse(domainName), RecordType.Mx);

            if (IsFailedQuery(dnsMessage))
            {
                // TODO: Throw specific type
                throw new Exception($"Dns query for {domainName} failed.");
            }

            var mxRecordsByPreference = 
                dnsMessage.AnswerRecords.OfType<MxRecord>().OrderBy(item => item.Preference);

            var result =
                (from record in mxRecordsByPreference
                 select record.ExchangeDomainName.ToString().ToLowerInvariant()).Distinct().ToList();

            return result;
        }