Computer Applications eamil working and protocols

computer application email working

1. Computer Applications B.A/BSC. IT, 5 th Sem

2. E-MAIL What is an E-mail? Email stands for Electronic Mail . It is a method to send messages from one computer to another computer through the Internet. It is used in every field. e.g. business, education, government, technical communication, and document interactions. It allows communicating with people all over the world. Multiple E-mail Clients: Gmail Outlook Proton Mail , many more.

3. Working of E-mail Open an E-mail client software and compose a new mail. Send the mail. The mail is transferred to mail server(computer system responsible for storing and forwarding emails). Mail server analyses the mail and identifies the route to send the mail to the recipient. The mail reaches the recipient/destination mail server. Mail server transfers the mail to the recipient email address or account.

4. Components of E-mail Basic components of e-mail system: User Agent (UA) Message Transfer Agent (MTA) Mail Box Spoof File User Agent (UA) A program used to send and receive mails. Also known as Mail Reader. It accepts variety of commands for composing, receiving and replying to messages

5. Mail Transfer Agent (MTA) Responsible for transfer of mail from one system to another. To send a mail, a system must have client MTA and system MTA. It transfer mail to mailboxes of recipients if they are connected in the same machine. It delivers mail to peer MTA if destination mailbox is in another machine. The delivery from one MTA to another MTA is done by Simple Mail Transfer Protocol.

6. MAIL BOX It is a file on local hard drive to collect mails. Delivered mails are present in this file. The user can read, delete according to his/her requirement. To use e-mail system each user must have a mailbox . Access to mailbox is only to owner of mailbox.

7. Spoof File This file contains mails that are to be sent. User agent appends outgoing mails in this file using SMTP. MTA extracts pending mail from spool file for their delivery. E-mail allows one name, an alias, to represent several different e-mail addresses. It is known as mailing list. Whenever user have to sent a message, system checks recipient's name against alias database.

8. Advantages and Disadvantage of E-mail Easy and Fast: Composing an email is very simple and one of the fast ways to communicate. We can send an email within a minute just by clicking the mouse Secure: Email services are a secure and reliable method to receive and send information. Mass Sending: We can easily send a message to many people at a time through email. Multimedia Email: Email offers to send multimedia, documents, images, audio files, videos, and various types of files.

9. Disadvantages Malicious Use: Anyone can send an email just by knowing their email address. An anonymous user or unauthorized person can send an email if they have an email address. The attachment feature of the email be the major disadvantage of it, hackers can send viruses through email because sometimes the spam feature unable to classify suspicious emails.  Spam: Days email services improve this feature. To improve this feature sometimes some important email is transferred into spam without any notification.  Time-Consuming: Responding through email takes more time rather than other message services like WhatsApp, Telegram, etc. Email is good for professional discussion but not good for casual chatting. 

10. Email Protocols What are Email Protocols? Email protocols are a collection of protocols that are used to send and receive emails properly. The email protocols provide the ability for the client to transmit the mail to or from the intended mail server. Email protocols are a set of commands for sharing mails between two computers. Email protocols establish communication between the sender and receiver for the transmission of email. Types of Email Protocols: SMTP POP IMAP

11. Simple Mail Transfer Protocol (SMTP) It is used to send mails over the internet. It is an application layer and connection-oriented protocol. It uses TCP port 25 for service. SMTP is used twice in sending the mail, one between sender and sender mail server, other between sender mail server and receiver mail server. It uses commands and responses to transfer the messages between two mail servers. Some of the SMTP commands are HELLO, MAIL FROM, RCPT TO, DATA, QUIT, VERIFY, SIZE, etc.

12. Post Office Protocol (POP) POP3 is a message access protocol that enables the client to fetch the mail from the remote server. It allows to access mail offline and thus, needs less internet time. To access the mails, it has to be downloaded. POP doesn’t have search functionalities. Port number used by POP3 is TCP 110. Some of the POP commands are LOG IN, STAT, LIST, RETR, DELE, RSET, and QUIT.

13. Internet Message Access Protocol (IMAP) It is also used to retrieve mails. IMAP4 is the current version. IMAP has more features and is more powerful as compared to POP. It uses TCP port 143. IMAP allows to access email without downloading them and also supports email download. It enables all email operations such as creating, manipulating, delete the email without reading it. IMAP allows you to search emails.

14. REFERENCES https://www.geeksforgeeks.org/computer-science-fundamentals/what-is-an-email/ https://www.geeksforgeeks.org/computer-science-fundamentals/introduction-to-electronic-mail/ https://www.geeksforgeeks.org/computer-networks/email-protocols/