Email, short for "electronic mail," is a method of exchanging digital messages between people using electronic devices, such as computers or mobile phones. It is a popular means of communication because it is fast, convenient, and can be sent to anyone worldwide with an email address.
An email address typically consists of three parts: a username or account name, a domain name, and a top-level domain. The username identifies the specific user's email account, while the domain name specifies the email service provider and email server that manages the user's email account. For example, in the email address [email protected], "john.smith" is the username, "example" is the domain name, and ".com" is the top-level domain.
The Mail User Agent (MUA) is an email client software that allows users to compose, read, and manage their email messages. It is a program or web-based service that enables users to send, receive, and manage email messages.
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Mail user agent (mua) program
1. Microsoft Outlook:- This is a popular email client that comes as part of the Microsoft Office suite. It allows users to manage email, calendar, tasks, and contacts all in one place.
2. Mozilla Thunderbird:- This is a free and open-source email client that is available for Windows, macOS, and Linux. It includes features like message filtering, advanced search, and support for multiple email accounts.
3. Windows Mail:- This is the default email client for Windows 10. It allows users to manage multiple email accounts and includes features like a calendar and task manager.
4. Apple Mail:- This is the default email client for Mac computers and iOS devices. It includes features like message threading, smart mailboxes, and integration with other Apple applications.
5. Sylpheed:- This is a free and open-source email client for Windows and Linux systems. It includes features like message filtering, support for multiple email accounts, and a plugin system for extending functionality.
6. KMail:- This is a free and open-source email client for Linux systems. It includes features like message filtering, support for multiple email accounts, and integration with the KDE desktop environment.
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Mail user agent (mua) web-based programs.
1. Gmail:- This is a popular web-based email client that is part of the Google suite of applications. It allows users to access email from any device with internet access and includes features like spam filtering and conversation threading.
2. Outlook.com:- This is a web-based email client that is part of the Microsoft suite of applications. It allows users to manage email, calendar, tasks, and contacts all in one place.
3. Yahoo Mail:- This is a web-based email client that is part of the Yahoo suite of applications. It includes features like a calendar, task manager, and integration with other Yahoo applications.
4. Zoho Mail:- This is a web-based email client that is part of the Zoho suite of applications. It includes features like message filtering, support for multiple email accounts, and integration with other Zoho applications.
5. ProtonMail:- This is a web-based email client that is focused on security and privacy. It includes features like end-to-end encryption, message expiration, and support for self-destructing messages.
6. FastMail:- This is a web-based email client that includes features like message filtering, support for multiple email accounts, and integration with third-party applications.
A Mail Transfer Agent (MTA) is a type of software application that manages the transmission of email messages from one computer or server to another. It is also known as a mail server or SMTP (Simple Mail Transfer Protocol) server.
A Mail Delivery Agent (MDA) is a software program that handles the delivery of email messages from the email server to the recipient's mailbox. It is responsible for storing the email messages in the appropriate mailbox, where they can be retrieved by the recipient using a mail client. The MDA is typically used in conjunction with a Mail Transfer Agent (MTA), which is responsible for routing email messages between different email servers.
The MDA uses either the Post Office Protocol version 3 (POP3) or the Internet Message Access Protocol (IMAP) to deliver email messages to the recipient's mailbox.
Simple Mail Transfer Protocol (SMTP) is a protocol used for transmitting email messages between servers on the internet. It is the standard protocol used for sending email messages and is responsible for the delivery of email from the sender's mail server to the recipient's mail server.
The most common ports used by SMTP are:
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Port 25 - This is the default port used for non-encrypted communication. It is used for sending email messages from one server to another over the internet.
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Port 465 - This is the port used for SMTP over SSL/TLS (Secure Sockets Layer/Transport Layer Security) encrypted communication. It is used to send email messages securely over the internet to protect the email data from interception or eavesdropping.
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Port 587 - This is the port used for SMTP submission. It is used by email clients to submit email messages to the mail server for delivery.
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Port 2525 - This is an alternative port used by some mail servers for SMTP submission. It is not an official port number, but some mail servers use it to avoid issues with port 587.
Internet Message Access Protocol (IMAP) is a protocol used for retrieving email messages from a mail server to an email client. It is an alternative to POP3 (Post Office Protocol version 3), which is another protocol used for email retrieval.
By default, the IMAP protocol uses two ports for communication:
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Port 143 - This is the default IMAP port used for non-encrypted communication. When a client connects to the server using this port, the communication between them is not encrypted, which can leave the email data vulnerable to interception or eavesdropping.
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Port 993 - This is the port used for encrypted communication using IMAP over SSL/TLS. When a client connects to the server using this port, the communication is encrypted, providing an extra layer of security and protecting the email data from interception or eavesdropping.
Post Office Protocol Version 3 (POP3) is a protocol used for retrieving email messages from a web server to a local email client, such as Microsoft Outlook or Thunderbird.
When an email client connects to a POP3 server, it downloads copies of the messages stored on the server to the client's device. This allows the user to read and manage their email messages without needing to remain connected to the internet or the server.
By default, the POP3 protocol uses two ports for communication:
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Port 110 - This is the default POP3 port used for non-encrypted communication. When a client connects to the server using this port, the communication between them is not encrypted, which can leave the email data vulnerable to interception or eavesdropping.
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Port 995 - This is the port used for encrypted communication using POP3 over SSL/TLS. When a client connects to the server using this port, the communication is encrypted, providing an extra layer of security and protecting the email data from interception or eavesdropping.
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Header: The header of an email contains information about the message, such as the sender and recipient email addresses, the date and time the message was sent, and the subject line. It also contains any additional information such as the email's priority, the type of content, and any message IDs or tracking codes.
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Body: The body of an email contains the main content of the message, including text, images, and links. It can also contain formatting, such as bold or italicized text, and may include signatures, disclaimers, or legal notices.
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Attachment: An attachment is a separate file that is sent along with the email message. Attachments can be any type of file, such as documents, images, or videos, and are often used to share files or data between the sender and recipient.
Email tracking is the practice of monitoring the delivery and open rates of emails, as well as other actions taken by recipients, such as clicking on links or downloading attachments. Email tracking typically involves embedding a small image or tracking pixel in the email content, which allows the sender to receive information about when and how the email was opened and accessed.
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Email spoofing is the practice of forging the email header to make it appear as if an email message was sent from a different sender than the actual sender. In other words, email spoofing is a technique used by attackers to make an email message appear to come from a legitimate source, such as a trusted organization, to trick the recipient into taking an action that benefits the attacker. Email spoofing can be used for a variety of malicious purposes, such as phishing scams, social engineering attacks, and malware distribution.
Preventing email spoofing requires the use of email authentication protocols, such as SPF, DKIM, BIMI and DMARC, which verify the authenticity of an email message and the identity of the sender.
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SPF (Sender Policy Framework) - SPF is an email authentication method that verifies the IP address of the email sender authorized to send emails for the domain in question. SPF records are added to a domain's DNS records and specify which IP addresses are authorized to send emails on behalf of the domain. When an email is received, the recipient's email server checks the SPF record to verify the authenticity of the email sender.
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DKIM (DomainKeys Identified Mail) - DKIM is an email authentication method that verifies the email was sent from an authorized domain by digitally signing the email header using encryption keys. DKIM records are added to a domain's DNS records and are used to verify the authenticity of the email message and the identity of the sender.
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BIMI (Brand Indicators for Message Identification) - BIMI is a newer email authentication method that allows domain owners to display their brand logo in the email recipient's inbox if the email message passes authentication checks. BIMI works by using DMARC to verify the authenticity of the email message and then using a verified logo file to display the brand logo in the email client. BIMI is designed to help improve brand recognition and combat phishing attacks.
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DMARC (Domain-based Message Authentication, Reporting, and Conformance) DMARC is an email authentication method that uses both SPF and DKIM to provide a comprehensive authentication framework for email messages. DMARC also provides a reporting mechanism to help domain owners monitor the email activity associated with their domain. DMARC policies are added to a domain's DNS records and specify how email servers should handle emails that fail authentication checks.
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