XG Firewall is impersonating the whole subnet for port 25

Hello John Felix Rodrin ,

Thank you for reaching out to the community, yes it is. 

Good day Vivek Jagad ,

Thanks for your immediate response. As it is a normal behavior, is this due to a feature or something? If you can share me a document or short explanation why is sophos capable of doing this as I need to discuss this with my boss. Unfortunately, there was no proper transition from the previous network administrator as such i'm currently studying the environment at my work. Thank you once again

Unfortunately, we do not have any documentation on this to provide you. 

Could you do a Packet Capture on the firewall and check, how the firewall response to this? 

Check for the firewall rule. Do you use the SMTP MTA? Do you have the firewall rule in place for ANY to ANY Scan SMTP?