POP vs. IMAP: The Basics
POP and IMAP are both protocols used for retrieving email from an email server so you can read messages on your device. They’re used when connecting to your email account from a desktop email app, like Thunderbird, Outlook, Apple Mail, Spark, or similar. You don’t need to worry about these email protocols when you use webmail (such as Gmail.com), because the service handles it all for you.
POP stands for Post Office Protocol, and is the older of the two. It was created in 1984 as a way to download emails from a remote server. Two revisions that added some enhancements, called POP2 and POP3, followed in later years. POP3 is still the current version of the protocol, though this is often shortened to just POP. While POP4 has been proposed, it’s been dormant for a long time.
IMAP, or Internet Message Access Protocol, was designed in 1986. Instead of simply retrieving emails, it was created to allow remote access to emails stored on a remote server. The current version is IMAP4, though most interfaces don’t include the number.
The primary difference is that POP downloads emails from the server for permanent local storage, while IMAP leaves them on the server while caching (temporarily storing) emails locally. In this way, IMAP is effectively a form of cloud storage.
The Workflow Differences Between POP and IMAP
To properly compare POP and IMAP, let’s look at a simplified version of how they each work.
The POP Workflow
When using POP, the email client first connects to the email server. Once it’s successfully connected, it grabs all the mail on the server. It then stores this mail locally on your device so you can access it in your email client. Finally, it deletes the mail in question from the email server before disconnecting. This means that the messages then only exist on the device you downloaded them to.
Note that while POP will delete mail from the server by default, a lot of POP setups allow you to leave copies of your email on the server. This can be useful if you’re worried about losing your mail, but if your mail provider doesn’t offer much server space, it can cause you to run out quickly.
How IMAP Works
IMAP works a little differently than POP. After it connects to the email server, it fetches whatever content you requested, like all new email or the contents of a specific message. This is cached locally, so you can work on your device. Once you make changes to your email, such as deleting messages or sending a new email, the server processes and saves these changes, then disconnects.
IMAP is a little more complex than POP, but the biggest aspect to remember is that all changes with IMAP happen on the server. You aren’t downloading local copies of all your messages; you’re using the email client to manage the email stored on the server. The only information stored on your device (unless you explicitly download something) are cached copies for efficiency.
Pros and Cons of POP and IMAP
Now that you know how they each work, what are the benefits and drawbacks of using POP or IMAP?
Advantages and Disadvantages of POP
POP was designed for a simpler time when you only needed to access your email from one device. In those days, constant internet access also wasn’t common, so POP made sense for dial-up connections where you got online, did what you needed, and then disconnected. It thus has the following pros:
- Mail is stored locally, so it’s always accessible even without an internet connection.
- An internet connection is needed only for sending and receiving mail. Managing it works fine offline.
- It saves server storage space, since old messages are deleted from the server automatically.
- You have the option to leave copy of mail on the server, giving flexibility if needed.
- If you like, it’s possible to consolidate multiple email accounts and servers into one inbox.
POP has some advantages in specific situations, but it’s largely outdated today. It’s not designed for checking email from multiple devices, so you can experience problems even if you leave a copy of email on the server. For instance, if you delete an email on one device, that deletion doesn’t sync to the server, so other devices will still have that message. And since each device downloads every message from the server, it’s easy to end up with a bunch of duplicates and not know what you’ve already dealt with.
Downloading every message from your POP account can use up a lot of space on your device, depending on how much mail you have. A lot of POP use today is to access mailboxes provided by your ISP, web hosting company, or similar, which tend to suffer from extremely limited storage.
Advantages and Disadvantages of IMAP
As mentioned earlier, IMAP was created to allow remote access to emails stored on a remote server. The idea is to allow multiple clients to manage the same inbox, which is in line with how most people use email today. So whether you log in from your home or work computer, you will always see the same emails and folder structure, since they are stored on the server. All changes you make are immediately synced to the server, so you don’t have to worry about confusing duplicated inboxes.
As a result, IMAP has the following advantages:
- Mail is stored on the remote server, so it’s accessible from multiple devices.
- All changes are tracked on the server, preventing duplicate inboxes, sent messages existing on just one device, and similar issues.
- Faster overview, as only headers are downloaded until content is explicitly requested.
- Mail is automatically backed up, as long as the server is managed properly.
- Saves local storage space by not requiring your computer to download all messages.
- You have the option to store mail locally if needed.
While an internet connection is needed to access mail using IMAP, it’s still possible to work offline and sync changes when you’re back online. The only major drawback of IMAP, which is also a problem with POP, is that most email providers offer a limited amount of space. Thus, you may need to clean out your email often if you have lots of messages in your account.
POP vs. IMAP: What’s Right for Me?
In almost every case, we recommend IMAP over POP today. There’s a good chance that you’ll want to access your email from at least two devices, and doing so with POP is a huge headache. Since every email service worth its salt supports both, there are no compatibility concerns.
However, if you’re still not sure, below are a few points to help you decide whether to use IMAP or POP:
Choose POP if:
- You only access your mail from a single device, and never plan to access it from another.
- You need constant access to all your email.
- Your don’t have a consistent connection to the internet.
- You have limited server storage.
Choose IMAP if:
- You want to access your email from multiple devices.
- You have a reliable and constant internet connection.
- You want to receive a quick overview of new emails or emails on the server.
- Your local storage space is limited.
- You are worried about backing your emails up.
What About Microsoft Exchange?
While POP and IMAP are supported by every modern email service, you’ve likely seen another entry when setting up mail: Microsoft Exchange. Also called Exchange ActiveSync, this option uses Microsoft’s Messaging Application Programming Interface (MAPI) to fetch email and other data so your mail client can read it. In addition to email, MAPI can sync other data like calendars and contacts.
If you use Outlook on your computer at work, or if your company has email powered by Microsoft 365, you’ll use Exchange for your email protocol. It’s similar to IMAP in functionality, but is more specific to Microsoft’s services.
POP and IMAP: Your Mail, Delivered
It’s important to know how POP and IMAP work so you can make the right choice for your email needs. Remember that if you use webmail, the service handles all this, so you don’t have to think about it. But next time you set up a new email app on your phone or computer, you’ll know how both of these protocols handle mail. IMAP is almost always the right choice, unless you have some specific reason to go with POP.