जेव्हा मेल हस्तांतरित करणारी संगणकीय आज्ञावली सर्व्हरशी संपर्क करते आणि टी सी पी जोड निर्माण करते, तेव्हा दोन संगणकीय प्रोग्रॉम अनुसरतात ज्यामुळे एखादा प्रेषक स्वतःची ओळख निर्माण करतो, स्विकारणाऱ्याला निर्देशित करतो आणि ई-मेल संदेश हस्तांतरित करतो.

The correct answer is Option A (SMTP).

Key Points:
• Simple Mail Transfer Protocol (SMTP):
• SMTP is an application layer, connection-oriented protocol running over TCP port 25 (or submission port 587) that governs the transmission of electronic mail across networks.
• Working Mechanism:
• When the client's Mail Transfer Agent (MTA) establishes a TCP three-way handshake with the recipient mail server, the two programs follow the SMTP handshake exchange:
• 1. `HELO` or `EHLO`: The sender identifies its domain to the server.
• 2. `MAIL FROM`: Specifies the sender's email address.
• 3. `RCPT TO`: Specifies the recipient's email address.
• 4. `DATA`: Transfers the body and payload of the email message.
• Other Protocols:
• ***HTTP* (Port 80): Web browsing and hypertext transfers.
• *FTP* (Port 20/21): File transfers.
• *TCP*: Transport layer foundation protocol, not the email application protocol itself.
• Hence, Option (1) is the accurate protocol.
• Key Takeaway**: SMTP (Simple Mail Transfer Protocol) is the TCP-based protocol used to identify senders, specify recipients, and transmit emails.