IMAP vs POP3: which should I use for my email?

When using an email app on your device to connect to your email accounts at HostM, you can choose between the IMAP and POP3 methods. Which should you choose and why does it matter?

Our quick and simple recommendation

It’s best to choose IMAP under most circumstances, and especially if you will be using multiple computers or devices to access the same mailbox.

Only choose POP3 if you use just one computer or device to access your email, never intend to use Webmail (i.e. access your email using a web browser), and want to configure your email app to remove your email messages from the server after they are downloaded to your computer or device.

IMAP: A quick summary

With IMAP, your email is stored primarily on the server.

Depending on your settings in your email app, some or all of the data may also be downloaded and stored on your computer or device, mainly as a cache to allow for faster access to the data.

Most actions that you take in your email app on messages in your mailbox affect the actual messages stored on the server.

For example, if you were to delete a message from your mailbox in your email app, the message is also deleted from the server.

If you have multiple computers or devices, you will likely want to set them up to connect to your mailbox via IMAP.

This way, when you delete a message, or mark a message as read, the server is notified and all of your computers or devices that connect via IMAP to the same mailbox are updated accordingly.

Choosing IMAP in your email apps is also recommended if you’d like to be able to use Webmail (access your email via your web browser) from time to time, since Webmail requires that your messages reside on the server.

Actions that you perform on messages via Webmail are also reflected in your email apps when connected via IMAP, and vice versa.

POP3: A quick summary

With POP3, your email is stored primarily on your computer or device.

Typically, with POP3, your email app does not leave messages on the server by default, although you can set it to do so (but see the section below for caveats).

In other words, when you download a message via POP3, it is typically then immediately removed from the server.

When connected via POP3, most actions that you take in your email app on messages in your mailbox affect only the messages stored on your computer or device.

These actions do not affect any messages that your email app may have left on the server.

For example, if you were to delete a message from your mailbox in your email app, it is deleted from your computer or device, but not from the server, even if there’s a copy of the message there.

Similarly, if you were to mark a message as read on your computer or device, the server is not notified of this.

What happens when you choose to leave messages on the server with POP3

Many email apps have a setting that allows you to leave messages on the server (either indefinitely or for a specific period of time) when connected via POP3.

As mentioned in the above section, with POP3, actions like deleting a message or marking a message as read in your email app do not affect the messages left on the server. They only affect the messages stored on your computer or device.

In addition, there is a small chance of your email app re-downloading all of the messages currently stored on the server at any time, even if they’ve been downloaded before (and even deleted or marked as read).

This is because when using POP3, the method that many email apps use to determine if a given message that it finds on the server has already been downloaded is not very robust.

Sometimes, a routine system or security update on the server might cause an email app to re-download every message that still remains on the server, causing you to have multiple copies of the same message.

For these reasons, if you’d like to store messages on the server for any reason, we recommend connecting via IMAP from your computers and devices.


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