POP3 vs IMAP

The most important differences between POP3 and IMAP

POP3	IMAP
Emails are downloaded. This means that each email message exists in full as a set of files on your device. The email message itself, and all attachments, signatures, etc, usually exist as separate files on your device. However some mail clients, notably Microsoft Outlook, might handle your email files differently.	Emails are synced. This means that The files making up each email (the message itself, and all attachments, signatures, etc.) are stored on the server, and your mail client may or may not keep these files on your device as well. When you sync your mail, your mail client fetches only the headers of the mail on the server and displays these to you as a list of the emails in your mailbox. The content of an email is usually only downloaded to your device when you click an email to read it, however you can change this behaviour with a setting in your mail client.
Downloaded emails can be left on the server or removed from the server, and this behaviour is controlled by a setting in your mail client. You can set your mail client to never delete mail from the server delete email from the server as soon as you download it delete mail from the server after a certain number of days delete email from the server when you delete it from your mail client	When you delete an email in your mail client, that email may be removed from the server, or or may be moved into the deleted items folder on the server.
Sent mail is not stored on the server.	Sent mail may or may not be stored on the server.
If you've sorted your email into folders, these folders exist on your device, not on the server.	Your custom folders exist on your device, and may or may not exist on the server.

If you're unsure of which you're using, you can check the account settings in your mail client. We've outlined how to do this below. Skip to the section that applies to your mail client:

Am I using POP3 or IMAP?

Your mail account could be configured as POP3 or IMAP, and this will determine how you'll need to proceed.

To find out which you're using, you'll need to check your email account settings.

Outlook

• In Outlook 2010 or 2013
  1. Click File.
  2. ClickAccount Settings.
  3. Click the Email tab.
• In Outlook 2016 or 2019
  1. Click File
  2. Click Account Settings.
  3. Click the new Account settings option that appears.
• In Outlook 2021 and 365
  1. Click File
  2. ClickAccount Settings
  3. Click Manage Profiles
  4. Click Email accounts

For all versions of Outlook, you'll see a list of your email accounts with Name and Type. Take note of the Type of your email account, which will be listed as IMAP/SMTP or POP3/SMTP.

Thunderbird

1. Click on the main Menu button.
2. Go to Options and select Account Settings.
3. Click Server Settings
4. Take note of Server Type which will be listed as IMAP Mail Server or POP3 Mail Server.

Apple mail

• MacOS 13
  1. Open the Mail app
  2. Click Mail
  3. Click Settings
  4. Click Accounts
  5. Select your account on the left
  6. Click the Server Settings tab on the right
  7. The incoming server will be listed at the top of the Server settings tab like Incoming Server (IMAP) or Incoming Server (POP3)
• MacOS 12 and earlier
  1. Open the mail app and click Mail
  2. Click Preferences
  3. Click Accounts
  4. Click the Server Settings tab on the right
  5. The incoming server will be listed at the top of the Server settings tab like Incoming Server (IMAP) or Incoming Server (POP3)