USING C PROGRAMMING IN LINUX

Today you will implement the classic 'mail' command of UNIX that was (once upon a time) used by most of us to send emails. 'mail' is a program that negotiates a connection with a server and sends an email using SMTP (Simple Mail Transfer Protocol). SMTP is a simple text protocol. The following messages are sent between a client and an SMTP server on port 25 in the following order: 1. Client sends the "EHLO command with an argument equal to the hostname of the machine initiating the connection on port 25 2. Server sends an ack or a reject 3. Client sends the MAIL command with the return address for the message, which has the following form mail to: , and is ended by . 4. Server sends an ack or a reject 5. Client sends the RCPT command with the recipient address for the message, which has the following form rcpt to: and is ended by . 6. Server sends an ack or a reject 7. Client sends the "DATA" command to signal the beginning of the message text 8. Server sends an ack or a reject (If it can receive the message or not) 9. The message contain one or more lines of text. To terminate the message, the last line must be a period with a single linefeed. The message is terminated with: In 10. Server sends an ack or a reject (If it accepts or rejects the methods)