How to resolve the various Undeliverables by Exchange 2003

Posted on 2007-10-02
Last Modified: 2013-11-30
Here's the complete error message (there are several like this)
: on 10/2/2007 11:43 AM
            You do not have permission to send to this recipient.  For assistance, contact your system administrator.
            < #5.7.1 smtp;554 5.7.1 Service unavailable; Client host [] blocked using; Dynamic IP Addresses See:

The irony is we are not listed on, I don't know whose IP address that is (not ours).
We're using GFI Mail Essentials but I tested with that service not running and it returns with the exact error message.  I'm also checking with GFI, awaitiing their response.  Frustrating!!
Question by:Valvatterott
    LVL 104

    Accepted Solution

    Do the error messages refer to the same IP address every time?
    Do you send email via another host?
    Have you checked to see who the IP address is issued to, whether it is your ISP or not?

    WHOIS says this

    Final results obtained from
    Results:, Inc. DSL-NET-5 (NET-208-41-0-0-1) -
    Sunfast/Associates Realty IEN-SFASREAL (NET-208-41-190-160-1) -

    # ARIN WHOIS database, last updated 2007-10-01 19:10
    # Enter ? for additional hints on searching ARIN's WHOIS database.

    LVL 8

    Expert Comment

    1. Go to and let them have check your mail server, mx records, spam lists etc.
    2. Check your reverse dns records
    3. If you don't have SPF, make a DNS SPF record. SPF stands for Sender Policy Framework and each domain should have a SPF record in DNS. See

    Author Comment

    The Email  Server used to go through DSL.NET until about a month ago, then these Undeliverables.

    Author Comment

    The dynamic IP listed is always the same, it looks like DSL.NET's.  Maybe I should call them now?
    I went through, checked through the MX, the Reverse DNS, and spam lists - all cool.
    LVL 104

    Expert Comment

    You have accepted my answer. Is the problem resolved?


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