Inbound Mail Problem SMTP / Edge to Exchange

  • Hi
    i try to translate my german thread. it looks like nobody could help me in the german section.

    Problem: I have a problem to transfer the incoming mail from dmz to lan. (See the attachment)

    Edge / DMZ =
    Exchange =
    INT-DNS = internal DNS Server

    Incoming Mail:
    Internet -> DMZ Edge Mailrelay / Mailforwarder -> Exchange Server = all emails stay in queue on DMZ Mailrelay with error "451 4.4.0 DNS query failed"

    telnet exchange 25 = OK.
    telnet exchange 587 = Ok.

    Outgoing Mail:
    Exchange -> DMZ Edge Mailrelay / Mailforwarder -> internet = all mails arrive @recipient / Ok.

    Rules: @ETH1

    Proto   SRC   Port   Dest         Port   GW
    UDP     *      *     Int-DNS      53      *
    TCP     *      *     Exchange    25      *
    TCP     *      *     Exchange    587     *
    TCP    DMZ   *     *               25      WAN1
    TCP    DMZ   *     *               587     WAN1

    Someone an idea? If you need more information about the rules or something pls post…

    Thanks for your help...

    if you want reply in german:,57002.0.html

  • How is the exchange server listed In the mail forwarder? If you put in the ip instead of a name, does the mail flow as expected?

  • atm i'm in xmas holidays. I will try to change this option… Do you think the DMZ Server is unable to resolve the the hostname? i write down my experience asap...

    Thanks for the fast reply.. merry xmas

  • just a guess. the rules seems to be okay. there is probably not any routing problems, so long as everything if using the pfense as its gateway.

  • I didn't foud the problem. I solved my problem by installing pfsense 2.0.2 on a different Dell Server with different hardware. That is not really a solution!

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