Our ISP has required us to switch our SMTP traffic from port 25 to 587. (Interesting note: We are a business with a business account.)
I have duplicated the STMP configuration lines in our firewall, replacing “SMTP” with “587”. I think the port is now open.
Someone claims they are not seeing traffic sent on port 587, and has asked us to prove it is not an issue on our firewall. We are receiving traffic on port 587.
Would there be additional steps after opening the port such as setting some kind of authentication or encryption in the firewall for port 587?