Which component is NOT part of the SMTP mail transfer process?

The web browser is not part of the SMTP mail transfer process. SMTP, or Simple Mail Transfer Protocol, primarily deals with the sending and receiving of emails between mail servers and email clients.

In this context, a mail server is responsible for receiving and routing emails, an email client is the application that users interact with to compose, send, and read emails, and a relay server is a server used to forward emails from one server to another until it reaches the final destination. All these components are integral to the functionality of SMTP.

On the other hand, a web browser operates primarily to retrieve and display web pages from the internet. While it may be used to access web-based email services, it does not directly participate in the email transfer process defined by SMTP. This distinction helps clarify the specific roles of different components in the overall framework of email communication.