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We have an application server that hosts a CRM application. It is using SMTP on it's own server to send emails. If I send an email using the application to, it shows up in my inbox. If I send an email to, it never shows up. It doesn't matter what address I put in for, they never get through. Any email addresses outside our domain/firewall get through.

We're using Exchange 2007 and when I look at the message tracking logs, the missing messages don't show up there, either.

Is there something I need to configure in Exchange or the SMTP server on the application server? I can't figure out why emails get outside the firewall but internal emails never show up.



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Sounds like a dns issue. What is the ip address that nslookup gives you when you do an mx lookup for your domain.

My guess is the ip address that comes back is the public ip and not the private ip. Your firewall probably isn't allowing the connection to come back in.

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See if this is possible:

  1. Your application server is configured in the domain
  2. When it sends an email to, it sends email to self and ultimately the email double bounces and is lost.
  3. This problem does not come it for other domains because the emails are delivered to outside.

If this is the case, you can just change the FQDN configured with the Application server to some other dummy domain.

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