Email

What Exactly Is Electronic Mail?

Email, or electronic mail, is a method of transmitting digital messages using electronic devices over computer networks. It operates across various networks, primarily the Internet and local area networks (LANs), and uses store-and-forward models to ensure reliable delivery.

The Evolution of Email

When Did Email Begin? The term ‘electronic mail’ was first used in 1975. However, variations like ‘e-mail’ have been in use since 1979. The preferred form is now widely accepted and recommended by style guides.

The Early Days of Computer-Based Messaging

Computer-based messaging emerged in the early 1960s with notable implementations in 1965 and 1971. Conventions for sending mail messages were refined over a series of Request for Comments (RFC) documents, leading to the development of proprietary electronic mail systems in the 1970s.

The Standardization of Email

How Did SMTP Come About? The Simple Mail Transfer Protocol (SMTP) was implemented on the ARPANET in 1983, marking a significant milestone. LAN email systems emerged in the mid-1980s, with CompuServe’s HPMAIL becoming the world’s largest selling email system.

The Rise of Standard Protocols

Once restrictions ended in 1995, SMTP, POP3 (Post Office Protocol 3), and IMAP (Internet Message Access Protocol) became the standard protocols for exchanging emails. These protocols ensure reliable delivery and management of messages across different devices.

The Journey of an Email

A typical sequence of events includes:

• Formatting and Sending: The MUA (Mail User Agent) formats the message and sends it to the local mail submission agent (MSA) using the submission protocol.
• Determining Destination: The MSA determines the destination address, resolves the domain name, and gets the fully qualified domain name of the mail server.
• Routing Messages: DNS servers respond with MX records listing the mail exchange servers for that domain. The MSA then sends the message to the message transfer agent (MTA) server, which may forward it before reaching the final message delivery agent (MDA).
• Delivery and Storage: The MDA delivers the message to the mailbox of user bob.

Alternatives and Complications

A variety of alternatives exist, including corporate email systems with internal formats and vendor-specific protocols. Alice may connect to a webmail service instead of having an MUA on her computer, while Bob can pick up his email in various ways, including logging into mx.b.org or using webmail services.

Reliability Over Speed

Email pre-dates instant messaging and prioritizes reliability over speed due to unreliable network links and busy servers. Reasons for slower delivery include large numbers of recipients, large attachments, multiple server processing, overloaded servers, and DNS response issues.

The Structure of an Email Message

Email messages consist of header and body sections. The header contains fields such as From, To, Subject, and Date, with a specific syntax according to RFC 5322. Each field has a name followed by a separator and a value.

Header Fields Explained

• From: Email address and author name
• Date: Local time and date of composition
• To: Email address and recipient name
• Subject: Brief summary of the topic
• Cc: Carbon copy recipients
• Bcc: Blind carbon copy recipients
• Content-Type: Information about message display
• Precedence: Indicating automated responses or prioritization (Microsoft Exchange respects the X-Auto-Response-Suppress field to prevent automatic responses from being delivered again)
• Message-ID: An automatically generated field that prevents multiple deliveries and serves as a reference in In-Reply-To
• In-Reply-To: Links related messages together by referencing the message ID of the original message
• List-Unsubscribe: Provides an HTTP link for users to unsubscribe from mailing lists
• References: Include the Message-ID of the original message and subsequent replies
• Reply-To: Used to reply to a message, while Sender displays the address of the sender acting on behalf of the author
• Arc-Authentication-Results: Provides authentication results for the email message
• Dkim-Signature: Ensures that the message has not been tampered with during transit

Email Body Content

The message body content includes encoding standards such as quoted printable, base64, 8BITMIME, and BINARY to transmit non-ASCII data. Character set specifiers enable transmission of international character sets using Unicode. Most modern graphic email clients allow users to use plain text or HTML for message bodies at their option.

Email Clients and Protocols

Programs used by users for retrieving, reading, and managing email are called mail user agents (MUAs). Email clients may mark messages as ‘read’ when opened. Mail can be stored on the client, server side, or both places. Standard formats for mailboxes include Maildir and mbox.

Types of Email Clients

• Web-based email: Using a web browser to send and receive email, typically without downloading messages due to internet connection requirements.
• POP3 (Post Office Protocol 3): Allows downloading messages on a local computer and reading them offline.
• IMAP (Internet Message Access Protocol): Provides features to manage mailboxes from multiple devices, shows message headers, sender, subject, and requires download of specific messages.
• MAPI (Messaging Application Programming Interface): Used by Microsoft Outlook to communicate with email server products.

Email in the Workplace

Email facilitates logistics, helps with synchronization, reduces cost, increases speed, and creates a written record of communication. 83% of U.S. knowledge workers found email critical to their success and productivity at work in a 2010 study on workplace communication.

Business and Organizational Use

Email marketing is often used via ‘opt-in,’ but without permission, it may be viewed as unwelcome ’email spam.’ Personal computer users access their emails from friends and family, while mobile devices have increased accessibility to email. Mobile apps allow for checking email on-the-go, with approximately 1.4 billion email users worldwide and 50 billion non-spam emails sent daily.

Issues and Challenges

Email issues include attachment size limitations, information overload due to increasing volumes of emails received by knowledge workers and employees, and the risk of receiving work-related emails outside working hours, leading to increased stress and decreased satisfaction with work. Email ‘spam’ is unsolicited bulk email that can reduce productivity and has become increasingly sophisticated, with malicious content or links making up a significant proportion of spam.

Security Concerns

Email spoofing occurs when an email message appears to come from a trusted source but is actually designed to mislead the recipient. Email bombing involves sending large volumes of messages to overwhelm a target address and cause it to become unusable. Privacy concerns arise due to the lack of encryption in email, the need for intermediate computers before reaching their destination, and the storage of emails on mail servers.

Conclusion

Email has come a long way since its inception, evolving from simple text messages to multimedia-rich communications. While it remains an indispensable tool for business and personal use, challenges such as spam, security concerns, and information overload continue to shape its future. As technology advances, so too will the ways in which we communicate via email.