We are having issues with our KBOX sending emails to unknown users. It looks like these emails are using the full internal domain name for its "from" email address. For example, we see our registered users getting emails from 'kbox@mma.edu'. We have that defined in the (Email Alias): for the Queue, which works fine. However unregistered users are getting an email error saying local delivery failed to 'kbox@kbox.campus.mma'.  Campus.mma is our internal domain.

Our goal is to have the "Unknown Email Address Response " sent to these unknown users as it provides instructions on what they need to do to become registered users.

Keep in mind we do NOT have "Accept email from unknown users" checked as we don't want account created each time an email from an unknown user arrives. 

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  • You will need to post more info.

    Exchange Server? Office 365? Gmail?

    Make sure your MX Records are fine, check them against the the same DNS you have in your Network settings, use this guide:

    If you see MX entries populated , then it's time to check your Receive Connector in exchange.

    send connector in exchange = is inbound to k1
    receive connector in exchange = outbound from k1
  • We are using FirstClass as our email server. MX records check out OK.

    What I'm not understanding is why a non-registered user changes the way our kbox handles that outbound email.
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