What is the difference between POP and IMAP?

If you are not sure which e-mail protocol, IMAP or POP, you want to use to setup your e-mail program refer to the following basic differences between these two protocols and choose the one that fits your needs.
The e-mail protocol is the procedure which your e-mail program will use to communicate with the server on which your e-mail messages are stored.

The POP protocol will download all the messages from the e-mail server onto your computer/device. This means that all the actions performed on the messages (reading, moving, deleting...) will be performed on your computer/device.
Because everything is kept on the user’s computer/device, the user will not be able to reopen messages from any location other than the computer where the messages have been downloaded.
Email programs do have an option to 'Leave a copy of the messages on the Server' for a predetermined period of time. If this is set on all computers/devices connecting to the mail server for say 14 days, then any device that connects within that 14 day period will get a copy of the mail on the Server. Once the 14 days pass the mail will be deleted from the server.

The IMAP protocol, by default, allows the user to keep all messages on the server. It constantly synchronizes the e-mail program with the server and displays what messages are currently present. All the actions performed on the messages (reading, moving, deleting...) will be done directly on the server. The connecting computer/device will need a live internet connection to view the complete mail.

Using IMAP limits the ammound of mail that can be retained, because there is a quota on our shared hosting servers (currently 1 GB). It is necessary to regularly delete unnecessary e-mail messages from the server, to avoid problems. If the mail box is full anyone sending to that email account will receive a notification that the accounts mailbox is full and the mail will not be delivered.

In the case of using a POP connection, the client is not limited by the amount of free space on the server. The limitation is the size of the hard drive on the personal computer.



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