Overview
Texas A&M Technology Services closed port 25 on the campus firewall in the effort to increase security, reduce spam, and prevent data leakage. If you are manually configuring an email client to send outgoing mail, it must use a secure protocol.
Information
Port 25 is the default communication port for unsecured SMTP email. Because it is unsecured, many forms of malware make use of the port to send spam email from infected computers. Malicious messages and spam can be curtailed by closing the unsecured port and requiring authorization.
Due to port 25's unsecured nature, sensitive data (such as Social Security numbers or academic records) can be leaked via port 25 when it is sent to an off-campus email server. The campus firewall can prevent these type of leaks when messages are sent through the approved port 587.