Joe, a customer, states that since the new firewall has been installed, he has not been able to send email. Which of the following ports on the firewall should be checked?

The correct answer is B. 25. SMTP (Simple Mail Transfer Protocol) uses port 25 and is responsible for sending (outgoing) email between mail servers and from email clients to servers. When a new firewall blocks outbound port 25, users can no longer send email. Port 21 is FTP (file transfers). Port 110 is…

Networking

Question

Options

A21
B25
C110
D443

How the community answered

(60 responses)

B
95% (57)
C
2% (1)
D
3% (2)

Explanation

SMTP (Simple Mail Transfer Protocol) uses port 25 and is responsible for sending (outgoing) email between mail servers and from email clients to servers. When a new firewall blocks outbound port 25, users can no longer send email. Port 21 is FTP (file transfers). Port 110 is POP3, used for receiving/downloading email - if this were blocked, the user could not receive email, not send it. Port 443 is HTTPS for secure web browsing. Since Joe's complaint is specifically about sending email, port 25 (SMTP) is the correct port to investigate on the firewall.

Topics

#SMTP#port 25#firewall ports#email protocols

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