How does email transmission work over the internet?

Email transmission over the internet involves a process called Simple Mail Transfer Protocol (SMTP) for sending and receiving messages.

Email transmission is a fundamental part of internet communication, and it operates using a protocol known as Simple Mail Transfer Protocol (SMTP). SMTP is a set of rules that govern the process of sending and receiving emails over the internet. It's a text-based protocol, meaning it communicates in human-readable text to send and receive messages.

When you send an email, your email client (like Outlook or Gmail) sends the message to your email server, which then uses SMTP to transmit the email across the internet. The email server breaks down the email into parts, including the sender's address, the recipient's address, the subject line, and the body of the message. Each part is then sent separately and reassembled at the recipient's end.

The email server communicates with the recipient's email server using SMTP commands. The sending server initiates the conversation with a 'HELO' or 'EHLO' command, followed by the sender's email address. The recipient's server responds with a code to indicate whether it's ready to receive the email. If it is, the sending server sends the 'MAIL FROM:' command, followed by the sender's email address. The recipient's server again responds with a code to confirm receipt.

Next, the sending server sends the 'RCPT TO:' command, followed by the recipient's email address. The recipient's server responds with a code to confirm that the recipient's address is valid. The sending server then sends the 'DATA' command, followed by the body of the email. The recipient's server responds with a code to confirm that it has received the email.

Finally, the sending server sends the 'QUIT' command to end the SMTP conversation. The recipient's server responds with a code to confirm that it has ended the conversation. The email is then stored on the recipient's server until the recipient opens their email client to check their email.

In summary, SMTP is a robust and efficient protocol that enables the transmission of emails over the internet. It uses a series of commands and responses to ensure that emails are correctly sent and received.