Turn off / Disable Default Internal Relay


  • I am going crazy over this, I have dozens on instances of Exchange running, one of the clients complained that he was doing tests and can send email using an SMTP tool without even being on the IP list of the relay connector. 

    Upon checking I found that if I used one of the accepted domains in the recipient the mail regardless of any connector there or not, would just pass and the email will be sent out. Not only that I can change the sender address to anything. If I use <g class="gr_ gr_545 gr-alert gr_spell gr_inline_cards gr_run_anim ContextualSpelling ins-del" data-gr-id="545" id="545">any</g> external address in the recipient then it won't work (Need an external relay right...).

    I have spent too many hours trying to get this restricted but cannot, because I cannot find a straight answer anywhere. My very straight question here is, is this really by default?

    Has anyone overcome this?

    9 กรกฎาคม 2561 16:53


  • Please remove the HTML from your post so we can read it.

    Is the SMTP traffic going through a load balancer in front of the Exchange server?  Unless it's configured to preserve the source IP address, that will break IP address-based filtering on receive connectors.

    Look at the settings of all receive connectors to make sure that you really understand what's happening.  If you have specific questions, post the relevant settings of your receive connectors--in text form, not a picture, please--with your question so we don't have to guess about how you have things configured.

    Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."
    Celebrating 20 years of providing Exchange peer support!

    9 กรกฎาคม 2561 23:00
  • Hi Shehryar Hussain,

    Any update now?
    If the above suggestion helps, please be free to mark it as answer for helping more people.


    Kyle Xu

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    16 กรกฎาคม 2561 10:07