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    Problem Enabling Mail to be sent out via SMTP from a server in our DMZ

      I have a server in our DMZ running PostFix on CentOS who is sending mail fine inside of our network.

       

      However, when I try to send mail outside the network it isn't passing through. I believe this is due to our Sidewinder firewalls stopping the mail from escaping our network.

       

      I have an SPF DNS entry for the SMTP server so I don't believe that is the issue either.

       

       

      The details of the rule I have setup to allow SMTP are below...can somebody please look it over and tell me where the problem lies?

       

       

      General:

      • Action: Allow
      • Service: smtp (Mail Proxy)
      • Audit: Standard (recommended)

       

      Effective Times:

      • Time Period: <Any>

       

      Source:

      • Burb: DMZ
      • Endpoint: DMZ smtpserver.domain.com
      • NAT: <None>

       

      Destination:

      • Burb: external
      • Endpoint: <Any>
      • Redirect: <None>
      • Redirect port: blank

       

      Trusted Source:

      • Enable TrustedSource: NOT checked

       

      Inspection:

      • Application Defense: default (smtp)
      • Level: None
      • IPS Signature Group: <None>

       

      Authentication:

      • Authenticator: <None>

       

       

       

      Thanks in advance for any help that can be provided.

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