Initial situation:

The SEPPmail Secure E-Mail Gateway is to be integrated into an existing email infrastructure. A Sophos UTM is already present as an upstream antispam relay. To be able to scan incoming, encrypted emails there, emails decrypted by the SEPPmail Secure E-Mail Gateway are to be sent to the Sophos UTM again without creating a loop.

 

Solution:

Sophos UTM generally sends all emails to the SEPPmail Secure E-Mail Gateway. Based on the markers to be set (X-headers), it decides whether the email is to be sent to the Sophos UTM for another scan or to the internal email servers (see also Routing On The SEPPmail Secure E-Mail Gateway).