What is the default port for SMTP (unsecured)?

What is the default port for SMTP (unsecured)?

• A. 465
• B. 22
• C. 514
• D. 25

Answer: (D)

The question tests knowledge of standard SMTP port numbers. The default port for SMTP traffic without encryption is 25. This port is traditionally used for mail transfer between servers and for client-to-server submission when no TLS is negotiated. Other ports serve different purposes: 465 was historically used for SMTP over SSL (SMTPS) but is not the standard unsecured port; 587 is the modern submission port for clients with STARTTLS; 514 is used for syslog, not SMTP; and 22 is for SSH. So the unsecured SMTP traffic typically goes through port 25.

The question tests knowledge of standard SMTP port numbers. The default port for SMTP traffic without encryption is 25. This port is traditionally used for mail transfer between servers and for client-to-server submission when no TLS is negotiated.

Other ports serve different purposes: 465 was historically used for SMTP over SSL (SMTPS) but is not the standard unsecured port; 587 is the modern submission port for clients with STARTTLS; 514 is used for syslog, not SMTP; and 22 is for SSH. So the unsecured SMTP traffic typically goes through port 25.