You have just built a new mail server for your organization that previously was using a cloud-based service. Unfortunately, you are finding that external sites are timing out when attempting to send mail to your new SMTP server. What port should you enable in your firewall to allow your mail server to properly communicate?
A) tcp/25
B) tcp/110
C) tcp/143
D) udp/161
E) Tell everyone you have a new zero-mail security policy
The answer: A) tcp/25
Simple Mail Transfer Protocol uses TCP port 25 to communicate. If you have a mail server inside of your firewall, then you’ll need to open this port to allow your inbound mail to properly arrive.
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Want to know more? Watch “Troubleshooting Mail, FTP, and Proxy Settings.”The TCP/IP protocol is the foundation of today’s network connectivity. In this video, you’ll learn about the TCP/IP settings and some of the loopback and automatic addressing functionality of the protocol. |