Which of the following is the default port used by the SMTP (Simple Mail Transfer Protocol)?

Correct option is B

The default port used by SMTP for email transmission is 25. It is primarily used for relaying emails between mail servers. Modern SMTP implementations may also use other ports for specific purposes, like 587 for message submission or 465 for encrypted communication.
Important Key Points:
1. SMTP Port 25:
· Port 25 is the default and most widely used port for SMTP communication.
· It is used for sending emails between servers but may often be blocked by ISPs to prevent spam.
2. Modern SMTP Ports:
· Port 587: Used for submitting emails from clients to servers.
· Port 465: Commonly used for SMTP over SSL/TLS for secure email transmission.
Knowledge Booster:
· 80: Port 80 is used for HTTP traffic, not SMTP.
· 110: Port 110 is used for the POP3 protocol, which retrieves emails from a server.
· 143: Port 143 is used for the IMAP protocol, allowing email access and synchronization.
· 465: This port was initially assigned to SMTPS (SMTP Secure) and is still used for encrypted SMTP communication.