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IMAP and POP or POP3 are used to access e-mail accounts, but were originally developed for different use cases. This results in specific advantages of the protocols in certain usage scenarios. The Internet Message Access Protocol is generally better suited for current e-mail applications. What advantages does IMAP have to offer in detail?
How do IMAP and POP3 differ?
The main difference between IMAP and the Post Office Protocol Version 3, so the full name says, is the range of functions. It results from the different objectives in the development of the protocols. POP3 is designed to download e-mail messages from a mail server so that you can save, read, and edit them on a local computer. IMAP, on the other hand, targets use cases where you leave your e-mail messages permanently on the mail server and only temporarily download the individual message you want to read or edit. You can also use both protocols in the other scenario, but they do not have their specific advantages.
What is advantageous about POP3?
The Post Office protocol is deliberately kept simple and can therefore be implemented with little effort. If you do not need the advanced functionality of IMAP, POP3 therefore offers you a streamlined system for accessing your E-mail. However, this use case is rather rare nowadays. Typically, you have a single workstation computer on which you regularly read, edit and, if necessary, archive your e-mail and use a powerful mail program as a mail user agent (MUA).
Historical peculiarities
The approach of POP3 is also due to the fact that until the 1990s you usually had very little space available on the mail server. You therefore had to empty your mailbox regularly to prevent it from overflowing. In the meantime, not only has the average storage space on mail servers increased considerably. Access to e-mail accounts is also much more frequent from different and often mobile devices. IMAP was developed for such scenarios, although the current versions of both protocols date back to 1996.
How do the differences
The different alignment of the protocols is also reflected in the usual default settings. Both systems use a delayed mechanism for deleting e-mails. This works similar to the trash on the PC desktop. While this virtual trash can is automatically emptied when accessing via POP3 but normally when logging off from the mail server, the Internet Message Access Protocol by default only deletes the trash after an explicit request by the e-mail client via the Expunge command. However, this behavior is usually configurable for both IMAP and POP3 in the MUA, so it is not a decision criterion for one of the protocols.
What specific advantages does IMAP offer?
Because the Internet Message Access Protocol leaves e-mail messages on the mail server by default and downloads them only when needed, it is particularly suitable for e-mail use with multiple end devices, each of which is permanently connected to the Internet or connects to it immediately when needed. This scenario has been the norm since the late 1990s, especially with the increasing use of mobile devices after the turn of the millennium. The selective downloading of messages saves data volume in mobile use, and if you want to read your e-mails regularly from different devices, this requires that the messages remain on the server until they are finally deleted.
In addition, IMAP offers extensive functions for handling mailboxes, which may also be structured and arranged hierarchically. Using IMAP, you can create new mailboxes on the server and rename or delete existing ones, move messages from one mailbox to another, you can search the contents of mailboxes according to various criteria, and you have the option of marking e-mails with so-called flags. All these functions are standardized in IMAP and only differ in the user interface on different e-mail clients. For example, deleting messages in IMAP is also realized by setting a flag that marks the e-mail as deleted. Before you have executed the Expunge command that permanently removes the messages marked in this way, it is therefore in principle possible with IMAP to search for deleted e-mails in the same way as for new, read, replied and so on. However, whether and how you can use these functions in practice depends on the e-mail client you are using. Some of these offer very different accesses to the same basic functions provided by the Internet Message Access Protocol.
