Hi, Sometimes we get calls from customers that cannot reach us by mail, they get the following error: #5.0.0 smtp; 5.1.2 - Bad destination host 'DNS Hard Error looking up mail.gediflora.be (A): NXDomain' (delivery attempts: 0), other get this message: smtp; 5.1.2 - Bad destination host 'DNS Hard Error looking up mail.gediflora.be (MX): NXDomain' (delivery attempts: 0) Could anybody help me? I looked everywhere but none have the answer. Best regards, Brecht

Brecht, The "exact" errors that you will see when someone tries to send to you are going to vary depending on the sending mail server. However, both of these seem to indicate a DNS error. The first thing I would guess is that you sometimes have DNS issues, however, I checked the name servers handling your domain (gediflora.be) and you have 4 name servers. They are all on the same IP subnet, but you do have 4 servers servicing name requests for you. nslookup -q=ns gediflora.beServer: mydomaincontroller.mydomain.comAddress: 198.201.27.67 Non-authoritative answer:gediflora.be nameserver = ns3.skynet.begediflora.be nameserver = ns4.skynet.begediflora.be nameserver = ns1.skynet.begediflora.be nameserver = ns2.skynet.be ns3.skynet.be internet address = 195.238.3.19ns4.skynet.be internet address = 195.238.3.20ns1.skynet.be internet address = 195.238.3.17ns2.skynet.be internet address = 195.238.3.18 Are all of the sending systems also in Belgium? Or other places in the world? Perhaps this is a IP connectivity issue and sometimes they just can't connect to the IP network where your DNS servers are hosted? Could you get a DNS server to host secondary DNS zone? One other thing to check is to make sure that whoever set up ns1.skynet.be has set it up correctly? I did a DNS query directly against it for mail.gediflora.be and recognize the domain. > set type=a> mail.gediflora.beServer: ns1.skynet.beAddress: 195.238.3.17 *** ns1.skynet.be can't find mail.gediflora.be: Non-existent domain

Hi Brecht, After some attempts using nslookup. It looks like the DNS query for mail.gediflora.be is not stable. I got the following results many times: Queried domain does not exist Maybe you could contact your ISP to see if there is something wrong. Regards, Elvis