Email Protocols: POP3 vs IMAP

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Learn about the difference between POP3 and IMAP email protocols, find out which one will serve your needs best, and learn about the potential consequences of your users choosing one over the other.


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POP3 and IMAP are both protocols for checking email. The method is set in your email client (Microsoft Outlook, Mozilla Thunderbird, etc.). For help setting up an email client, please see these articles in our Help Center.


In the past, the POP3 protocol was the most popular. With POP3, all of your email messages are downloaded to your computer and (under most standard configurations) deleted off the server.

When to Use POP3

The POP3 protocol is a good choice if you are checking email from a single device or computer. It reduces diskspace used on the server, because all of the email is downloaded and deleted.

This method also allows you to easily back up your email, as part of the process of regularly backing up other files on your main computer.

POP3 is the preferred choice of users with privacy concerns. E-mail can still be intercepted during the transfer process, but because it is stored on your computer and not the server, anyone who wishes to access your email (such as a law enforcement agency with a warrant) will need to come to you, not to the administrator of the server. With IMAP, your email is only as secure as the server where it is hosted.

When Not to Use POP3

If you frequently check email from multiple devices and computers, you may want to choose the IMAP protocol instead.


The IMAP protocol stores email on the server. If you sort emails into files or folders, these are also stored on the server, so the organization method is preserved regardless of how you access the account.

When to Use IMAP

In recent years, the IMAP protocol has rapidly gained popularity. The proliferation of smartphones, and the increasingly mobile nature of computing, means that it is most convenient for users to have all of their email stored on the server, so that it is accessible from anywhere on any device.

When Not to Use IMAP

The main down side to using IMAP is the diskspace usage. As an administrator, you may want to set limits on how much diskspace is allotted to each user. As a user, you may need to keep an eye on your email account, and delete emails and attachments as necessary to remain under the limit.