POP stands for “Post Office Protocol”. It helps people to access their email from a remote server. IMAP stands for “Internet Message Access Protocol”. It is also used to access email from remote server.
POP was originally developed in 1984. In 1986, Mark Crispin developed IMAP at Stanford University as a substitute for POP.
The first POP protocol requested username and password for downloading the email all in one go. IMAP is a two-way protocol and hence provides more functionality to the user.
In 1985, POP2 was released which had a greater number of commands and replies.It also allowed the user to download a single email instead of downloading all emails at the same time. The revised IMAP which was released quickly after the 1st version allowed for identifying commands and responses.IMAP2bis, released in 1990s, was the next revision which supported MIME (Multipurpose Internet Mail Extensions).
In 1988, POP3 was released, after that no other release has come so far. POP3 made retrieving email on personal computers in a simple, easy and efficient way. The next version of IMAP that came was IMAP4rev1 which was released in 1996.It allowed encryption of emails and passwords.
POP just downloads email to user’s computer and generally deletes them from the remote server. Hence, it downloads for storing the email on local storage permanently. IMAP allows the storage of email on remote server. It leaves the email on the server and stores them on local storage temporarily. It caches the email locally.Hence, it is a type of cloud storage.
If you have a number of devices on which you want to read your email such as laptop, phone or tablet, you will need to download or delete the same email on all devices. The two-way protocol of IMAP allows the synchronization of email of users on multiple devices.
The folders you create on one device would not reflect on other devices. Also, there won’t be any indication telling you which message was read, deleted or flagged by you. As there is synchronization of email on multiple devices, all these changes/ settings are reflected on any device you login to.
Those people who use computer to access their email account and take a back-up on their hard drive can use POP. For those who use various number of devices like mobile phones, tablets etc., IMAP is the better option as synchronization is the key for such use.
It is a slow process to download email if the number of messages stored on the server is large. IMAP is a lot quicker than POP as it provides advantage of downloading only the email headers.
After downloading the email from remote server, the POP disconnects itself from the server. Before getting disconnected from the server, IMAP processes what user has done to the emails such as marking as read, flagging or deleting etc.
In POP, since mail is stored locally, you can access it even without an Internet connection. Internet connectivity is only required while sending and receiving mails. In IMAP, since the mail is stored on the remote server, an internet connection is always needed to access the email.
Server storage space is saved. Local storage space is saved.
If you don’t want the mails to get deleted from the server, there is an option to keep a copy of email on the server. Even in IMAP there is an option to store the email locally. Also, mail gets backed-up automatically if the server has been properly managed.
Hence, choose POP if :·

  • Mail is to be accessed only from one device.
  • Irrespective of internet connectivity, access to mail is required.
  • Storage space on server is short.
Choose IMAP if :·

  •    Mail is to be accessed from different devices.
  • Internet connection is reliable and continuous.
  • Storage space is limited locally.
  • Back up is important.
  • Quick review of emails is required.