What Is Email? Email Definition and Guide

Since its introduction, email has become one of the most popular methods of digital communication. It's projected that over 4.37 billion people worldwide will use email by 2026. You can easily communicate with anyone across the world at any time, as long as they have an email account. In this article, learn what email is, how an email client and an email header work, and how to secure your email messages and account.

What is email?

Email, short for electronic mail, is the method of exchanging computer-stored messages between people over the Internet. It allows you to send even non-text files, such as audio files, videos, and images, as attachments.

It originates from the time of ARPANET, or the Advanced Research Projects Agency Network. In the 1970s, Ray Tomlinson is credited with sending the first electronic mail messages between two ARPANET computer systems. Since then, email has become the most widely used form of communication in both personal and professional settings.

With it, you can communicate with others regardless of their location as long as they have an email address and an Internet connection. These kinds of messages are fast, cost-effective, and convenient. They also work on both public and private networks.

Two clients exchanging a message via email

Electronic mail relies on several basic protocols within the TCP/IP suite such as SMTP, POP3, and IMAP. SMTP (Simple Mail Transfer Protocol) is used for sending these messages; POP3 (Post Office Protocol 3) receives them. Alternatively, some email systems use IMAP (Internet Message Access Protocol) in place of POP3 as it enables you to view messages from multiple devices anywhere.

How does email work?

Electronic mail messages are sent from email clients, which can be either software clients or web browsers. When you click Send after composing an message, it goes through several steps to reach the recipient's mailbox. Here's how email works:

  1. Compose an email. Once you create your message and establish a recipient, send the email to begin the process.
  2. The message goes to the SMTP server. A Mail Transfer Agent (MTA), which is the sender's mail server, initiates a SMTP connection. Your message goes through the SMTP server, which will send the message.
  3. Email verification occurs. The SMTP server checks and authenticates your electronic mail message in order to determine which server to send the message to.
  4. The SMTP looks for the recipient's server. The SMTP server then locates the proper server associated with the recipient's domain name. Once located, it sends your message over to the recipient's email server.
  5. The email arrives in the recipient's inbox. When the message arrives in the recipient's inbox, it remains there until the recipient "picks it up" by downloading it from the server. This occurs via IMAP or POP3 depending on the server.

Without the proper push and pull protocols, your message won't send or reach its destination. The process isn't complicated, but all of the above steps are important for email communication to work successfully.

Components of email

An email is comprised of three main components: the SMTP envelope, the message header, and the body.

SMTP envelope

The Simple Mail Transfer Protocol envelope is not visible to the end-users, but it plays a crucial role in the delivery process. It contains information used by mail servers to route and deliver the message. The SMTP envelope consists of two main parts:

  • Mail From, which specifies the electronic mail address of the sender. It indicates where bounce notifications and delivery status updates should go.
  • Recipient(s), which specifies the electronic mail address or addresses of the intended recipient(s). The SMTP envelope allows for multiple recipients to be included, enabling the message to be delivered to multiple recipients.


An email header contains essential metadata and routing information about the message. It's visible to both the sender and the recipient. If you want to trace an email, you need to analyze the email header. The header includes:

  • From: The field displays the sender's name and email address. It's automatically filled by most email clients.
  • To: This field indicates the primary recipient of the message. If the address is associated with a display name, it will show up in the field.
  • Subject: This field provides a brief summary or description of the message's content.
  • Date: This field shows the date and local time when the message was composed. It's a mandatory header field that the majority of clients fill out automatically.
  • CC (Carbon Copy): The email addresses of additional recipients who receive a copy of the message are listed in the CC field. The recipients can see the addresses listed in this field.
  • BCC (Blind Carbon Copy): This field allows additional recipients to be included in the email. Using both CC and BCC will send a copy to the listed recipients. However, recipients in the BCC field aren't visible to anyone except to the sender.
  • Reply to: This field specifies the electronic mailing address to which replies should go.

Other optional fields include Importance, X-Priority, Attachments, and more, depending on the client used.

Message body

The email body contains the actual contents of the message. It consists of text, images, attachments, and formatting. It's where the sender conveys their message, whether it's a simple text message, a formal business proposal, or a multimedia-rich newsletter. The body's structure and content are specified in the Content-Type field in the email header.

  • Text body. For plain text emails, the body contains the message's text in a simple, unformatted manner.
  • HTML body. For HTML-formatted emails, the body includes HTML tags and styles to render the message with various fonts, colors, and layouts. This allows for more visually appealing and interactive messages.
  • Attachments. The body can also include attachments, such as documents, images, or other files which the recipient can download and view separately from the text body.

All three parts of an electronic mail message work together to facilitate its delivery. Each component serves a specific purpose in the messaging ecosystem, ensuring that messages are properly addressed, routed, and presented to the recipients.

What do you need to send or receive an email?

To send and receive electronic mail, you need only a few things. First, you need an email client, which is a software application installed on your device that allows you to manage your electronic mail messages. Microsoft Outlook and Apple Mail, for example, are popular clients.

Alternatively, you can use a webmail service, like Gmail or Yahoo! Mail, by accessing it through a web browser.

You also need a valid email address and a valid destination address. Each address consists of a username and a domain name in the format of [email protected]. You can create an address through most email service providers.

Finally, for a successful exchange, you need an active Internet connection and an Internet-connected device. This can be your computer, tablet, or mobile device. With all of these elements, you'll be able to send and receive all types of emails successfully.

What is an email address?

An email address is a unique identifier used to send and receive electronic messages over the Internet. It consists of two main parts: a local-part and a domain part, separated by an at sign (@).

Take, for example, [email protected]. 'johndoe' denotes the local-part, and 'gmail.com' denotes the domain part. The combination of both creates a distinct electronic mail address that allows messages to go to the intended recipient.

Users can choose what they want for the local-part, but the domain name represents the email service provider or organization that manages the email account. The SMTP protocol uses the domain name system (DNS) to translate a domain name into its IP address before forwarding the message to the server.

Advantages and disadvantages of email


There's a reason why emails are one of the most common methods of communication today. Using it to send messages in both personal and professional settings has several advantages, including:

  • It's cost-effective. Compared to traditional postal mail, these kinds of messages are highly cost-effective.
  • It's fast and efficient. It allows for fast communication, as it only takes a few seconds to send and receive messages from anywhere.
  • It protects the environment. Electronic mail is, obviously, paperless; this cuts back on environmental costs.
  • You can attach files and documents. It allows users to attach files and documents, which helps share important information without the use of paper mail.
  • It has a global reach. This type of messaging connects people from different time zones and areas of the world.
  • It allows for asynchronous communication. Email works as asynchronous communication, meaning the sender and recipient don't need to be online simultaneously in order to exchange messages.


Though email is a popular method of communication, it has its risks like everything else. The disadvantages of using email include:

  • The potential for malicious use. Hackers often use spam emails to perform malicious activities. Additionally, users need to use caution with what messages they read; some contain malware that downloads when you open the email.
  • Security risks. This type of communication isn't entirely secure or private. While most providers take measures to protect user data, there's still a risk of unauthorized access.
  • A lack of immediate feedback. Unlike in-person or phone conversations, electronic mail messages don't provide instantaneous feedback. However, most methods of communication are asynchronous like this; if you need an answer immediately, your best bet is a synchronous form of communication like a phone call or video chat.

Is email secure?

Although email can be a secure method of communication, it's vulnerable to cyber threats. There are steps that users can take to protect their emails, like encrypting them, but even still, some attackers can intercept encrypted messages to get access to confidential information.

Because it's so commonly used - and less commonly secured - email is a common method of attack for cybercriminals. These criminals use email methods like email spoofing, phishing emails, and email spamming to conduct cyberattacks. All these incidents put the user at risk for threats like the spread of malware or ransomware.

Business email compromise, or BEC, is another email risk. BEC attacks involve impersonating a trusted individual or organization to deceive employees. These threats target businesses or groups of people. Other cybercriminals use manipulative social engineering tactics to try and coerce recipients to click links, send money, or otherwise take action.

How do you secure email?

Because email isn't inherently secure, users should employ additional security techniques for a safe experience. Try some of the following safety measures to protect any sensitive data exchanged in email communications.

  • Password rotations. You can protect your messaging accounts by using strong, unique passwords and changing them regularly.
  • Two-factor authentication (2FA). Two-factor authentication adds an additional layer of security to accounts. It sends a unique code to your mobile device in addition to your password, which protects your account from unauthorized access.
  • Spam filters. Using spam filters will help keep malicious messages out of your inbox.
  • Regular software updates. Keep your clients and operating systems up-to-date to protect against viruses and other threats.
  • Secure email gateways. Businesses can set up electronic mail security gateways to protect themselves from cyber threats.
  • Digital signatures. Aside from using automated email encryption software, electronic mail services should use digital signatures to protect messages in transit.

Additionally, make sure to be careful when it comes to any links or attachments in a messsage. Hackers often send malware or spyware through downloadable files in emails; proceed with caution, especially if the message comes from an unknown source.

Even if you're not a security expert, don't worry too much about your electronic mail security; most clients offer one of two primary encryption capabilities. They are Transport Layer Security encryption, known as TLS encryption, and end-to-end encryption, known as E2EE.

As an updated version of Secure Sockets Layer (SSL) emails, TLS emails are encrypted during transit. E2EE, on the other hand, makes it so that only the sender and the recipient of a message can decrypt it. These, combined with the safety measures above, make electronic mail a much more secure communication method.

Frequently asked questions

What is an email client?

An email client is a software application that lets users manage their mail accounts. It enables them to send, receive, organize, and compose messages. Popular clients include Outlook, Gmail, Thunderbird, Yahoo!, and Apple Mail.

What is the difference between email and webmail?

Email is a method of sending and receiving electronic messages, whereas webmail refers specifically to accessing, sending, and managing electronic messages through a web browser interface.

What is CC in email?

CC stands for carbon copy. In electronic mail messaging, it allows for you to send a copy of your message to someone besides original recipient listed in the "to" field. If you list someone as CC on your message, they will receive a copy and the original recipients will know that the CC'd person received one.

What is BCC in email?

BCC stands for blind carbon copy. In electronic mail communication, it allows you to send a copy of a message to someone besides the original recipient without their knowledge. If you list someone as BCC in your electronic mail message, they will receive a copy, but the original recipients won't know that a carbon copy went out to any BCC recipients.