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DNS problem question.

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  • 01-05-2002 11:30am
    #1
    mayhem#
    Registered Users Posts: 2,051 ✭✭✭


    Quick question lads, My ISP had some "DNS problems" as they describe it, lately. Could this cause email that I send to go missing? It's just that a small percentage of my emails lately have been unanswered and I am trying to find out what's happening...


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    #2
    The Cigarette Smoking Man
    Closed Accounts Posts: 649 ✭✭✭The Cigarette Smoking Man


    It depends on the mail server that's receiving the mail, if the server does a DNS lookup to see if the domain exists (to check if it's SPAM) and the domain doesn't exist it won't accept the mail.


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    #3
    Gaz
    Registered Users Posts: 1,586 ✭✭✭Gaz


    Did you get a mail failure notification ?

    If there DNS is down then the mail wont find its way onto the recipients domain but you should get a reply saying it couldnt be found.


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    #4
    steve-hosting36
    Closed Accounts Posts: 2,161 ✭✭✭steve-hosting36


    DNS will delay email, but eventually you should get a noticfication from the mail server if there was a fatal problem,

    Stephen


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    #5
    jmcc
    Registered Users Posts: 7,412 ✭✭✭jmcc


    Originally posted by The Cigarette Smoking Man
    It depends on the mail server that's receiving the mail, if the server does a DNS lookup to see if the domain exists (to check if it's SPAM) and the domain doesn't exist it won't accept the mail.

    Also if the receiving mailserver is running spam filtering software, it could be set to silently drop spam messages. If your ISP has recently appeared on some of the RealTime Blackhole listings for open relays (Eircom seemed to be on a few a while ago) then it may flag the message as spam or drop it. Alternatively as TCSM says, it may reject the mail.

    Generally if the message is rejected (a 550 message) then it the receiving server will refuse the message, the mail will bounce and you may get an error message.

    If the message cannot be delivered (a temporary failure (450 I think)) then your server will keep trying to deliver for about 5 days and if it fails after that it will delete the message from the queue.

    If your mailserver is one of the Hughes satellite service ones, it may be worth checking its IP with some of the RBL sites.

    If the mail was outbound when the ISP had DNS problems then it may not have been able to find the mailservers for the e-mail recipents. This probably would have resulted in an error (host not found) message for each failed e-mail.

    Regards...jmcc


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    #6
    greys
    Registered Users Posts: 112 ✭✭greys


    what I think could happen here is that the "DNS problem" your ISP is referring to, means that they have their DNS servers down. In practice they still have the way to ask other DNS servers with domain name queries and everything, giving you ability to continue web browsing and sending e-mail. But when your friends are trying to send you replies, their ISPs ask yours for names, and don't get an answer, as your ISP DNS servers are down or have some problems with managing queries. So, those friends are probably getting their mail returned to them saying that your address or mailserver isn't found, but your mail still goes out nicely.


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