IP address ranges and firewall settings

What are the IP ranges from which the Cleanmail Domain Gateway forwards e-mails? And how do I need to configure the firewall so that only e-mails sent from the Cleanmail Domain Gateway are accepted?

Please open the following IP ranges on the firewall for SMTP (port 25). We suggest that customers using on-premise Exchange 2013/16/19 open the port 2525 (for recipient verification, Exchange Backend).

Range 1: - (CIDR Notation:
Range 2: - (CIDR Notation:


Customers of the Cleanmail Archive service also need to open port port 143 (for IMAP access to the journaling mailbox using STARTTLS, if applicable) or port 993 (the same by using IMAPS) for the following IP address:

Primary91.208.173.180, net mask (CIDR Notation:

Mirror185.142.213.179, net mask (CIDR Notation: