POP versus IMAP

Most email providers offer two ways to setup your email when using an email client such as Outlook, Thunderbird, Apple Mail, or even your smartphone or tablet.

In this article I will explain what is the difference between POP versus IMAP protocols. So, lets get started.

POP (Post Office Protocol) server is a piece of software that gives an email user access to the email stored in the user’s account on that server. The user can download the messages using a MUA (email client) and store the email locally for later viewing.

IMAP (Internet Message Access Protocol) server is a software program running on a server that provides full access to all the folders the user has created on the server. The email user can synchronize all the folders and messages on the server with the data stored locally using a MUA with IMAP capabilities.

The original protocol is POP. It was created in 1984 as a means to download emails from a remote server. IMAP was designed in 1986 to allow remote access to emails stored on a remote server. Essentially, the main difference of the two protocols is that POP downloads emails from the server for permanent local storage, while IMAP leaves them on the server and just caches (temporarily stores) emails locally. In other words, IMAP is a form of cloud storage.

POP (Post Office Protocol)

When using this method messages are pushed to a device (computer, phone, tablet) and they stored there. The email leaves the sender and arrives in your Inbox without being stored on a server anywhere. There are settings that allow you to store copies of the message on your email providers server, but this is often not included in the default configuration. Once you have received an email, you have the message stored locally. You could be offline, completely disconnected from the internet, and still have access to the complete message.

The biggest downside to POP is if you don’t have the server configured to store your email. If you download all of your email locally and something happens to your computer, you’ve lost those messages forever. Because storage is cheap everywhere now, and email takes up very little space, for most people, there’s not a good reason not to store your messages on the server. If you’re using POP in a smartphone and storage is an issue, maybe if you’ve got an 8GB filled up with music, videos, photos and games, then storage may become an issue.

In simple words, POP protocol connects to the server, retrieves all mail, stores locally as new mails, deletes the mails from server (most POP clients also provide an option to leave a copy of downloaded mail on the server for a number of days) and disconnects.

IMAP (Internet Message Access Protocol)

When using this method messages allows users to access email from anything, as long as you have the username and password. With IMAP, the email lives on the server and you have access to some basic information about every email in your Inbox. When you want to see and interact with the email, the email is temporarily downloaded but not really stored on the machine you are using. The biggest benefit to IMAP is the ability to quickly access your email from just about any device — as long as you have a decent internet connection.

Unfortunately, if you’re without a fast connection or if you are somehow without internet entirely, then it won’t be possible to assess your emails. In some cases IMAP clients will download a week’s or so of email headers and store that information locally, but will not download images or attachments. If you need to search your inbox, and that email is more than a few weeks old, you have to have internet access to to retrieve it.

In simple words, IMAP protocol connects to server, fetch user requested content and cache it locally (list of new mail, message summaries, or content of explicitly selected emails), process user edits (marking email as read, deleting email etc) and disconnects.

POP Advantages

  • Mail stored locally, always accessible, load very quicly, even without internet connection.
  • Internet connection needed only for sending and receiving mail.
  • Saves server storage space.
  • Option to leave copy of mail on server.
  • It is widely supported by ISPs and email providers.
  • Consolidate multiple email accounts and servers into one inbox.
  • All email programs support it.

POP Disadvantages

  • If you have 1 or more mail clients then you can end up with mail on one client that isn’t on another.
  • E-mails and attachments are downloaded at the same time meaning you can’t read the message until they are both downloaded.
  • Messages are stored on your hard drive so they’re not accessible from other computers.
  • Sent mail and drafts are not accessible from other computers.
  • Messages are eventually removed from the server.
  • It’s usually difficult to migrate from one program to another, sometimes impossible.
  • Users normally don’t have backups of their email.

IMAP Advantages

  • Mail stored on remote server, accessible from multiple different locations.
  • Internet connection needed to access mail.
  • Faster overview as only headers are downloaded until content is explicitly requested.
  • Mail is automatically backed up if server is managed properly.
  • Saves local storage space.
  • Option to store mail locally.
  • IMAP mail folders remain synchronized with your webmail.
  • Sent messages and drafts are also stored on the server.
  • Server-side spam filtering is easily implemented with IMAP.
  • IMAP mail is backed up nightly on the server and can be restored.
  • Ease of migration from a program to a program and from a computer to another computer/location.
  • Ease of setting up additional computers to check your email, no need to copy anything from one computer to another.

IMAP Disadvantages

  • Messages load slower, in particular the first time they’re read.
  • Sensitive to size and requires periodic archival of email messages.
  • Subject to storage quotas.
  • Very few ISPs and email providers offer IMAP as it is considered a high end option and it’s complex for them to support.
  • Not all email programs support it properly.

What Is The Best Email Protocol For Me?

Obviously, it depends on your specific variables and you probably have an idea of what is best suited for your situation already. If not the points below should help to make a final decision.

Choose POP:

  • if you want to access your mail from only one single device.
  • if you need constant access to your email, regardless of internet availability.
  • if your server storage space is limited.

Choose IMAP:

  • if you want to access your email from multiple different devices.
  • if you have a reliable and constant internet connection.
  • if you want to receive a quick overview of new emails or emails on the server.
  • if your local storage space is limited.
  • if you are worried about backing up.

If in doubt, go with IMAP. It’s the more modern protocol, it allows you to be flexible, your email is automatically backed up on the server, available server space usually isn’t an issue these days, and you can still store important emails locally.

Please leave your comments below with what protocol did you choose.


Experienced IT Consultant working and living in the UK. In early years he was born and raised up in Greece and been to the UK since studies. He is passionate with technology, gadgets and computers, he really likes the internet and IT in general.

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