On the surface, POP and IMAP seem quite similar. However, the differences in the way they function have consequences for users and website owners alike.
POP
The Post Office Protocol 3, or POP3, is the most commonly used protocol for receiving email over the internet. This standard protocol, which most email servers and their clients support, is used to receive emails from a remote server and send to a local client.
A recipient or their email client can download mail periodically from the server using POP3. Thus, POP3 offers a means of downloading email from a server to the client so the recipient can view the email offline. POP3 can be thought of as a "store-and-forward" service.
Since emails are not kept on your server, you lack a secure backup system. When you download new messages to your computer, those copies are the only ones that exist. If something happens to your computer or you accidentally delete an email, there’s no retrieving the lost data.
However, some users find this as the best solution to free up space on the server for more emails to be received, hence remove the urge of upgrading their email storage. These users opt for other means of backup, e.g. backing up their computers on the cloud or offliene.
On the other hand, POP also ensures that, once you’ve downloaded your emails, you can interact with them fully without needing constant internet access. If you lose connection to the email server, you still have complete copies available of all your messages and their associated attachments.
IMAP
The advantages and disadvantages of IMAP are the direct opposite. The nice thing about IMAP is that your emails are all stored safely on the server. You can access them from anywhere, without altering or affecting the original copies. Plus, any changes you make in your email on one device will be transferred to any other device you use. For example, if you delete an email you this will take effect on all the devices and hence on the server. If you send an email, a copy will also be stored on all your devices and also on the server, this is unlike POP.
Of course, if you do lose connection to your internet, you’ll have a harder time working with your email when using IMAP. Most clients only store some information for each email locally. For example, they might save the message itself but not any attachments or images.
THE VERDICT
At the end of the day, there is no ‘right’ choice here. There is a case to be made that IMAP is a closer fit for our modern, always-connected lifestyle, and that its benefits outweigh the one real drawback. If you regularly use more than one device to access your email, IMAP is likely the better option, since it will sync your actions between various devices.
However, there’s still a place for POP, particularly if you only use a single device for email management. Plus, many modern POP clients let you choose to store emails permanently on the server, so you’ll still have a backup in place. Nevertheless, this option is mainly used by users to manage the storage on the email hosting accounts.
FREE UP SPACE
By default, when you retrieve new messages from a POP3 email account, the messages are deleted from the POP3 mail server and then saved on the computer that you are using. Because the message is no longer on the POP3 mail server, you can’t see it when you connect from another computer.
By changing the settings on your POP3 email account, you can choose whether the messages are removed after they're downloaded.
Follow these steps in Outlook 2013 or 2016:
- Via the navigation bar at the top left, go to “File”> “Account settings” and choose “Account settings” from the drop-down again.ь
- Select your mailbox and click on “change”.
- Click in the bottom right on “More settings” and go to the “Advanced” tab.
- Under “Delivery”, check the options “Leave a copy of messages on the server” and “Remove from server after removal from ‘deleted items'”. Optionally, you can also simply choose to automatically delete messages from the server after X number of days, for example after two weeks. The messages will still be on your computer but no longer on the server.
- Click “OK” to confirm and click “Next” to check the settings.
If all goes well, your deleted emails will be deleted from your e-mail server from now on.
