Additional information

SPF - Sender Policy Framework

If the customer has set up an SPF record for his email domains, the customer must include the following DNS A record to his SPF record:


The SPF is a technique to make it more difficult to falsify the sender of an e-mail.

IP addresses contained in the A Record:

Table 1: SPF Record IPs




Good Gateway

Good Gateway

BAD Gateway

DNS - Configuration Sender Mail Domains

To ensure a proper mailhandling over the Secure Mail Gateway it is necessary to create an MX Record or minimum an DNS A Record for the from customer used sender mail domain. Ideally the MX Record should point to a mailserver which is capable of receiving replies and NDR for the used mail domain.


In case there is no mailserver available for the used sender mail domain, then the reply-to header could be added to the outgoing mails. With this header it is possible to reroute the reply and NDR messages to an existing Mailbox (for example to an functional mailbox below an existing customer mail domain).