Question

Model the data processing that might take place in an e-mail system. You should model the mail-sending and mail-receiving processing separately.

Short answer

Model the mail-sending using SMTP for delivery, and the mail-receiving using POP3/IMAP for retrieval.

Step-by-step solution

Understand the Mail-Sending Process

The mail-sending process typically involves composing an email, attaching any necessary files, and specifying the recipient's address. Once the email is composed, it is sent to the Simple Mail Transfer Protocol (SMTP) server, which then communicates with the recipient's email server to deliver the email.

Break Down the Mail-Sending Steps

In the mail-sending process, start with the user composing an email. After the email is composed, the user then submits the email to the SMTP server. The SMTP server processes the email, authenticates the sender, and forwards it to the recipient's server using DNS to locate the recipient's server.

Identify Mail-Receiving Components

For receiving emails, we focus on incoming messages that arrive at the recipient's server. Here, Post Office Protocol (POP3) or Internet Message Access Protocol (IMAP) are used. The server receives the email from the sender's server and stores it in the recipient's mailbox.

Break Down the Mail-Receiving Steps

The mail-receiving process involves the recipient's server first accepting the email. The server then authenticates the message and checks for spam or malware. Finally, the message is stored in the recipient's mailbox, where the user can access it using an email client through either POP3 or IMAP.

Key concepts

Mail Sending Process

The mail-sending process is a vital part of any e-mail system. Understanding this process helps in smoothly sending electronic messages from one user to another. Sending an email begins when a user composes a message using an application. This message can include text, images, attachments, and more. Once composed, the email is sent by the user’s email client to a server called the Simple Mail Transfer Protocol (SMTP) server.
This SMTP server acts as a postman in the digital world. It packages the email and prepares it to journey across the internet to the recipient's email server. During this journey, the SMTP server will contact the recipient's email server by resolving the recipient's email domain name using DNS (Domain Name System) to route the email correctly. Only if the sending server (SMTP) is verified and authenticated, does the recipient’s server accept the email, ensuring a secure transaction.

Simple Mail Transfer Protocol (SMTP)

Simple Mail Transfer Protocol, or SMTP, serves as the primary protocol for sending emails over the Internet. It's like the postal system for emails, handling the delivery of outgoing mail from a sender to a recipient.
SMTP works in a step-by-step process. First, it establishes a connection with the recipient's email server using a handshake method which involves verifying the credentials of the sender and the servers involved. Then it transfers the email data. This includes the message body and any attachments via this secure connection.
SMTP uses specific commands like HELO, MAIL FROM, RCPT TO, DATA, and QUIT to execute the email transfer. Each command has a specific purpose, ensuring that emails are correctly processed and sent to the desired location. Remember, SMTP is only designed to send emails, not to receive them.

Mail Receiving Process

Receiving an email is as crucial as sending one. The process begins when the recipient's email server receives the digital mail sent to it from the sender's SMTP server. This server acts like a virtual post office, sorting and storing incoming messages. Once an email arrives, the server checks the message for spam and malware and authenticates the sender to ensure its trustworthiness.
If the message is clean and safe, it is then stored in the recipient's email mailbox. The emails remain on the server until the user accesses them through their email client, which can use either the Post Office Protocol (POP3) or Internet Message Access Protocol (IMAP) to retrieve the emails and view them.

Post Office Protocol (POP3)

Post Office Protocol version 3, commonly known as POP3, is one of the popular protocols used in receiving emails from a server. When a user wants to read an email, their email client connects to the email server using POP3. This protocol downloads all emails from the server to the user's local device and then usually deletes them from the server subsequently, freeing up space.
This method is beneficial for users who do not have a continuous internet connection but want access to their emails offline. However, its limitation is that once emails are downloaded and deleted from the server, they are not accessible from any other device.

Internet Message Access Protocol (IMAP)

The Internet Message Access Protocol, known as IMAP, provides a more flexible way to access and manage email messages directly on the email server. Unlike POP3, IMAP allows users to view and manage their emails via multiple devices simultaneously because it keeps all messages stored on the server.
IMAP synchronizes email data, showing the same view of the email inbox across all devices. This feature is perfect for people who frequently switch devices and need real-time updates on their emails. Users can read, delete, and organize messages without needing to download them. Such advantages make it highly popular among those who require constant access to their emails, regardless of where they are or what device they use.