Question

Describe e-mail protocols. For each one: functionality, architecture, send/receive process, advantages, disadvantages.

Answer 1

The email protocol is a method used to transmit or exchange information between email servers and clients. The three most familiar protocols are SMTP, POP and IMAP.

SMTP(Simple Mail Transfer Protocol):The SMTP protocol only can be used to send emails to a mail server from a mail client, not to receive emails.

Functionality/send or receive process:The most important functions those perform by SMTP are User verification and Delivery failed Notification. SMTP verifies whether the sender who 's accessing SMTP server has the authorization to send an email message, so we must have valid authorization such as SMTP username and password to access it. Furthermore, SMTP delivers the email messages to the recipients and verify whether the email messages are delivered successfully .If the email messages cannot be delivered. It will pull back and send an error message to the sender.

Advantages of SMTP: Reliability If the email is not successfully delivered, the SMTP server will try to resend the email until the transmission is successful. If the email really cannot be delivered to the recipient, the SMPT server will pull back and send an error message back to sender.

Simplicity SMTP is the simplest method

Disadvantages of SMTP:It is insecure .Another disadvantage is the server limitation

POP(Post office protocol ): It is generally used to support a single client. There are several versions of POP but the POP 3 is the current standard.

Functionality /send or receive process: POP servers set up mailboxes (actually directories or folders) for each e-mail account name. The server receives the mail for a domain and sorts it into these individual folders. Then, a user uses a POP client program (such as Outlook or Eudora) to connect to the POP server and download all the mail in that user's folder to the user's computer. Usually, when the mail messages are transferred to the client machine, they are deleted from the server.

Advantages of POP:Emails are downloaded to the user’s computer. Messages can be read when user is offline.

Less server storage space required; all emails are stored on local machine.

Disadvantages of POP:Emails cannot be accessed from other machines

Email folders can become corrupted, potentially losing the entire mailbox at once.

IMAP (Internet Message Access Protocol):Internet Message Access Protocol (IMAP) is an Internet standard protocol used by email clients to retrieve email messages from a mail server over a TCP/IP connection.IMAP allows simultaneous access by multiple clients. This is why IMAP is more suitable for you if you're going to access your email from different locations or if your messages are managed by multiple users.

Functionality /send or receive process: The IMAP architecture enables users to send and receive emails through a remote server, without support from a particular device. This type of email access is ideal for travelers receiving or answering emails from their home desktop or office computer.When a user requests an email, it is routed through a central server. This keeps a storage document for the email files.

Advantages :Ability to delete messages, search for keywords in the body of emails, create and manage multiple mailboxes or folders, and view the headings for easy visual scans of emails.

Disadvantage:The main disadvantage of the IMAP protocol is that it is mandatory to have an internet connection on all the time to read/reply and search the messages.

IMAP can be complex to maintain, and thus some hosts do not support the protocol.