POP and IMAP are what allow you to download messages from mail servers onto your computer so you can access your mail with a program like Microsoft Outlook, Apple Mail, or Thunderbird, even when you aren’t connected to the Internet.
POP allows you to use your Inbox, as the name suggests, like a post office. The email leaves the sender and arrives in your Inbox without being stored on a server anywhere. Once you have received an email, you have the message stored locally on your computer. You could be offline, completely disconnected from the internet, and still have access to the complete message.
Unlike POP, IMAP offers two-way communication between your web server and your email client. This means when you log in to your web server using a web browser, actions you perform on email clients and mobile devices will instantly and automatically appear in your webmail.
IMAP also provides a better method to access your mail from multiple devices. If you check your email at work, on your mobile phone, and again at home, IMAP ensures that new mail is accessible from any device at any given time.
Finally, IMAP offers a more stable experience overall. Whereas POP is prone to losing messages or downloading the same messages multiple times, IMAP avoids this through two-way syncing capabilities between your mail clients and your web server.
So, which one should you use? Although we generally recommend IMAP, if you have limited space on your email account, use POP. Otherwise, you email account will be full in no time.