Exchange - Undeliverable - Reverse DNS

Discussion in 'Windows Small Business Server' started by Don Tagliatelli, May 9, 2007.

  1. Hi,

    I get an undeliverable while sending to one specific recipient:

    There was a SMTP communication problem with the recipient's email server.
    Please contact your system administrator.
    < #5.5.0 smtp;554 Refused. Your reverse DNS entry contains
    your IP address and a country code.>

    I can't find any info about this error on the internet. Is this an issue at
    our provider?

    We're on a SBS 2003 SP1, no smarthost.

    Anyone an idea?


    Don Tagliatelli, May 9, 2007
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  2. The remote site is applying some sort of analysis to the PTR record
    (commonly called reverse DNS) associated with your public IP. This is
    pretty rare today, but will only become more and more commonplace as
    companies fight to keep spam to a manageable level.

    Best practice (ie complying with the RFCs [internet standards]) is to have
    that be the same as the name in your MX record, so if your ISP will
    co-operate, I'd arrange to change it.
    Steve Foster [SBS MVP], May 9, 2007
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  3. Thanks!

    I'll hear at our provider...

    Don Tagliatelli, May 9, 2007
  4. Don Tagliatelli

    Al Williams Guest

    We had email issues like this and ended up switching to the smarthost to
    avoid them. I figure the ISP's mailservers can deal with all the anti-spam
    measures out there better than I can. We haven't had an issue since but
    that may depend upon how good your ISP is.

    Allan Williams

    Al Williams, May 9, 2007
  5. What's your public IP address's reverse DNS ?
    Ping -a

    This is controlled by whomever owns your public IP/block....your ISP.

    ....or look up your domain at for more info.Is your domain? It has DNS problems -

    If it isn't your domain, contact whomever you're trying to correspond with
    and tell them their IT folks need to fix this. There's no A record for - and there needs to be.
    Lanwench [MVP - Exchange], May 13, 2007
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