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Email

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Electronic mail, or email, is a method for transmitting and receiving digital messages across computer networks. It functions as the digital counterpart to physical mail, using electronic devices to communicate. Today, email is a ubiquitous medium used in business, government, education, and entertainment. Most people consider having an email address a basic necessity for modern life. An email address typically follows a specific structure. It consists of a local-part, followed by the @ symbol, and then a domain name.

email
email

Modern email systems rely on a store-and-forward model. This model allows messages to travel even if the sender and recipient are not online at the same time. The process begins when a user employs a Mail User Agent (MUA). This is the software or interface used to read and write messages. The MUA formats the message and uses a submission protocol. This protocol is a specific profile of the Simple Mail Transfer Protocol (SMTP). The MUA sends the content to a local Mail Submission Agent (MSA).

email
email

The MSA then handles the routing of the message. It looks at the destination address to find the Fully Qualified Domain Address (FQDA). The part before the @ sign is the username, or local part. The part after the @ sign is the domain name. To find the correct server, the MSA uses the Domain Name System (DNS). The DNS server provides MX records, which are mail exchange records. These records list the specific mail exchange servers for that domain. The message is then sent to a Message Transfer Agent (MTA) server. This server might forward the message through several other MTAs before it reaches the final Message Delivery Agent (MDA). The MDA finally places the message into the recipient's mailbox. The recipient's MUA then retrieves the message using either POP3 or IMAP protocols.

email
email

The history of email began with computer-based messaging in the early 1960s. This was made possible by a development called time-sharing. In 1965, a notable implementation occurred through the CTSS project at MIT. By 1971, the first ARPANET network mail was sent. This historic transmission introduced the @ symbol to designate a user's system address. Throughout the 1970s, companies like IBM, CompuServe, and Xerox developed their own in-house mail systems. In 1983, SMTP was implemented on the ARPANET. While different systems competed for dominance, the combination of SMTP, POP3, and IMAP eventually became the global standard after 1995.

E-post från Wikipedia - 2019
E-post från Wikipedia - 2019

An email message is organized into two main sections called content. The first section is the header, and the second is the body. The header contains structured fields that provide essential information. These fields include "From", "To", "CC", "BCC", "Subject", and "Date". Each field name is followed by a colon and a value. The header and the body are always separated by a single blank line. Originally, email was a text-only medium using ASCII characters. However, the introduction of Multipurpose Internet Mail Extensions (MIME) changed this. MIME allows email to carry expanded character sets and multimedia content, such as images.

Mozilla Thunderbird 3.1
Mozilla Thunderbird 3.1

Sometimes, delivering an email can take longer than expected. There are several technical reasons why a message might be delayed. Large attachments require more time to transmit across the network. A message might also need to pass through many different servers. Sometimes, a mail server is overloaded due to a denial-of-service attack or a large amount of spam. If a server is busy, it may queue the mail. In fact, mail can be queued and retried for up to five days. If it cannot be delivered after that, the sender is notified of a permanent failure.

Evolution 36 mail
Evolution 36 mail

Email is deeply connected to the broader systems of global communication. It operates across local area networks and the massive infrastructure of the Internet. While it favors reliability over speed, it remains a fundamental tool for digital interaction. Users can interact with email through various interfaces, such as a webmail service or a dedicated desktop client. Even as newer technologies emerge, the structured protocols of email ensure that messages move predictably across the globe.

Evolution 36 mail
Evolution 36 mail
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File:Evolution 36 mail.png
Evolution 36 mail.png
File:E-post från Wikipedia - 2019.jpg
E-post från Wikipedia - 2019.jpg
File:email.svg
email.svg
File:Mozilla Thunderbird 3.1.png
Mozilla Thunderbird 3.1.png
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