What are POP3 and IMAP?
In today's information world, most communication is done through email. While you may know how to compile a message and send it or look at messages that have been sent to you, most are not aware of what goes on behind the scenes of this technology.
When you receive an email in your Inbox of your email application on your computer, such as Microsoft Outlook, it has been sent from your ISP (Internet Service Provider), such as your local cable company or Yahoo, via a mail server that resides on the ISP's network. The mail server acts as a post office and determines who should receive the mail and stores it in the recipient's mailbox on the server.
However, in order to receive your email messages, your email application connects with the server and retrieves the messages that are in your mailbox using POP3 (Post Office Protocol 3) or IMAP (Internet Message Access Protocol). These two protocols are standards used by most e-mail client software.
What is the difference between POP3 and IMAP?
The main difference between POP3 and IMAP is where the email messages are stored.
With POP3, the email messages are downloaded to your computer and then deleted from the ISP's mail server. However, in some cases, the ISP allows the option of leaving them on their server for a specific amount of time. Nearly all subscribers to individual email accounts use POP3 to access their email.
With IMAP, the email messages are stored on the mail server and viewed by the user through some type of user email interface. However, a user can download the message if they choose. IMAP is used primarily in large networks, such as college campuses. This prevents the tremendous overhead required in processing time and disk space from each email user downloading all of his or her messages onto their own computers or specified disk area.
Advantages of IMAP
- Multiple users can access the same mailbox. For example, several employees working in the same department, such as customer service, or employees working on the same project could view and manage email messages from one mailbox instead of needing a mailbox for each person. Through the use of flags defined in the IMAP4 protocol, clients can keep track of message state; for example, whether or not the message has been read, replied to, or deleted. The message stays on the mail server until someone deletes it.
- A user can search for a specific message by specifying a certain criteria.