Exactly How Emails Works – Steps and Explanation

Email is one of the most widely used methods of communication, allowing messages to be sent over the internet from one user to another almost instantly. But behind the scenes, several protocols and processes work together to ensure that your message reaches its intended recipient. Here’s a detailed explanation of how emails work, including the key steps and components involved.

Key Components of Email

1. Email Client: A software application that allows users to compose, send, and receive emails (e.g., Microsoft Outlook, Apple Mail, or webmail services like Gmail and Yahoo Mail).
2. Mail Server: A server that manages the sending and receiving of emails. It has two main types:
   • SMTP Server (Simple Mail Transfer Protocol): Handles the sending of emails.
   • IMAP/POP3 Server (Internet Message Access Protocol / Post Office Protocol): Handles receiving emails.
3. DNS (Domain Name System): Translates domain names into IP addresses, helping to route the email to the correct mail server.

How Emails Work: Step-by-Step Process

Step 1: Composing the Email

• User Action: A user writes an email using an email client (e.g., Gmail, Outlook).
• Email Content: The user provides the recipient’s email address, subject, and body content.
• Attachments: Users may also attach files to the email, like documents, images, or videos.

Step 2: Sending the Email

When the user clicks “Send,” the email client starts the process of delivering the email.

• SMTP (Simple Mail Transfer Protocol): The email client sends the message to an SMTP server.
  • The SMTP server belongs to the sender’s email service provider.
  • It is responsible for handling the transmission of the email to the recipient’s server.
• Email Structure: The message is sent with the sender’s email address, recipient’s address, message content, and any attachments.

Step 3: DNS Resolution

To deliver the email to the correct destination, the SMTP server needs to find the mail server associated with the recipient’s domain (e.g., example.com).

• DNS Lookup: The SMTP server queries the DNS (Domain Name System) for the MX (Mail Exchange) records of the recipient’s domain.
  • MX Records: Specify which mail servers handle emails for a particular domain.
  • A Records: Translate domain names into IP addresses so the SMTP server can locate the recipient’s mail server.

Step 4: Connecting to the Recipient’s Mail Server

Once the DNS resolution process provides the recipient’s mail server’s IP address, the sending SMTP server establishes a connection with the recipient’s mail server.

• SMTP Protocol: The email is transferred using the SMTP protocol from the sender’s server to the recipient’s mail server.
• Relaying: In some cases, the email may be relayed through multiple SMTP servers before reaching the recipient’s server.

Step 5: Receiving the Email

After the email reaches the recipient’s mail server, it needs to be stored and made available for the recipient to access.

• Mail Storage: The recipient’s mail server stores the email in the recipient’s mailbox on the server until the user retrieves it.
• POP3/IMAP Protocol: To access the email, the recipient’s email client communicates with the mail server using either:
  • POP3 (Post Office Protocol 3): Downloads the email from the server and often deletes it from the server after download (suitable for accessing email from a single device).
  • IMAP (Internet Message Access Protocol): Keeps emails on the server, allowing the user to access them from multiple devices and synchronize changes (e.g., read/unread status).

Step 6: Delivering the Email to the Recipient’s Inbox

The email client (e.g., Gmail, Outlook, Apple Mail) retrieves the message from the recipient’s mail server using POP3 or IMAP and displays it in the recipient’s inbox.

• Notification: The user receives a notification that a new email has arrived.
• Email Headers: When viewing the email, the recipient can see headers such as From, To, Subject, Date, and other metadata.

Protocols Involved in Email Transmission

1. SMTP (Simple Mail Transfer Protocol):
   • Used for sending emails.
   • Operates on port 25, 465, or 587.
   • Handles the process of relaying emails between servers and delivering them to the recipient’s mail server.
2. IMAP (Internet Message Access Protocol):
   • Used for receiving emails.
   • Operates on port 143 (unencrypted) or 993 (encrypted).
   • Allows users to access emails from multiple devices while keeping them synchronized.
3. POP3 (Post Office Protocol 3):
   • Also used for receiving emails.
   • Operates on port 110 (unencrypted) or 995 (encrypted).
   • Downloads emails from the server to a single device and optionally deletes them from the server after downloading.

Example: How Email Travels from Sender to Recipient

1. User A (Alice) composes an email to User B (Bob) using Gmail.
2. Alice’s email client (Gmail) sends the email to Gmail’s SMTP server.
3. Gmail’s SMTP server queries DNS to find the MX record for bob@example.com.
4. DNS returns the IP address of the mail server for example.com.
5. Gmail’s SMTP server connects to example.com’s SMTP server and delivers the email.
6. The mail server at example.com stores the email in Bob’s mailbox.
7. Bob opens his email client (e.g., Outlook) which connects to the example.com server using IMAP.
8. Bob’s email client retrieves the email and displays it in his inbox.

Key Terms and Concepts

• Email Headers: Contain metadata such as the sender, recipient, date, and subject. Headers also include technical details like the path the email took across servers.
• MIME (Multipurpose Internet Mail Extensions): Standard for formatting email content to support text, HTML, and attachments.
• SPF, DKIM, DMARC: Security mechanisms used to verify the sender’s identity and prevent email spoofing.

Conclusion

The process of sending and receiving emails involves several steps and protocols, each playing a critical role in ensuring that your message reaches its destination securely and accurately. Understanding how emails work can help users and administrators troubleshoot issues, configure email servers correctly, and maintain secure email communications. Whether it’s composing, sending, or receiving, the flow of emails relies on a seamless interaction between clients, servers, and DNS records.