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550 5.4.4 Error when using Contact to Relay mail

    Question

  • Hi!

    I have a customer who would like to use contacts to relay mails to external partners working for him. The problem is that when we send mails to this contact the sender receives a NDR with the code 550 5.4.4. We have been able to trace the problem back to the NoSpamProxy being used in the DMZ, because we can see the following in the logs:

    220   mail.<customer domain> ready

    EHLO   mail.<customer domain>

    250-mail.<customer domain>   welcome

    250-DSN

    250-ENHANCEDSTATUSCODES

    250-8BITMIME

    250   SIZE

    5985425

    MAIL   FROM:<Source Email-Address>   SIZE=15241

    250   2.0.0 Requested mail action okay

    RCPT   TO:<Name@Targetdomain>   ORCPT=rfc822;name@Customer Domain NOTIFY=FAILURE,DELAY

    550   5.4.4 Unable to relay

    QUIT

    221 2.0.0 Service closing transmission channel

    My guess is that the NoSpamProxy recognizes that the mail is being relayed and blocks it. I was wondering if any of you have had this problem and what your work-around is?

    Thanks for any and all input.

    Cheers,


    Gerrit


    If you think your to small to make a differnce, try going to bed with a mosquito in the room...

    Wednesday, January 11, 2017 9:47 AM

All replies

  • Hi 

    In your case what i understood is that you have created Mailcontacts to route emails to external partners

    So you are having mailcontact - Routes to your SMTP gateway NoSpamProxy and you get the NDR from them

    My guess is that the NoSpamProxy recognizes that the mail is being relayed and blocks it. I was wondering if any of you have had this problem and what your work-around is?

    You need to create a routing table in your SMTP gateway and define the route IP address of your partner to this mail contact domain so that the SMTP server will route these emails to them.

    This will work only if the SMTP route is defined to that destination Partners 


    Remember to mark as helpful if you find my contribution useful or as an answer if it does answer your question.That will encourage me - and others - to take time out to help you Check out my latest blog posts on http://exchangequery.com Thanks Sathish (MVP)


    Wednesday, January 11, 2017 2:35 PM
  • Hi,
    How about the issue?

    Are replies above helpful to you?


    Best Regards,
    David Wang
    TechNet Community Support


    Please remember to mark the replies as answers if they helped.
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    Tuesday, January 17, 2017 4:38 AM
    Moderator