POP3 and IMAP Explained.

POP3 and IMAP these protocols are used for retrieving email from an email server.  So for example if you’re using an email client such as Microsoft outlook, you would configure outlook with either POP3 or IMAP to retrieve your email on a computer. And you can also use these protocols on your tablet or smartphone to retrieve your email. So you can use either one, the choice is yours.

But the question is, which protocol do you want to use? Is one better than the other? So that’s what we’re going to talk about.

So let’s talk about POP3 first. Now POP3 stands for post office protocol 3. Now POP3 is the simpler of the two protocols because the only thing that POP3 does is download the email to your device from a mail server. And it only downloads what’s in your inbox folder, which is where your email is, and that’s pretty much it.  

, POP3 and IMAP Explained., TechRX

It doesn’t download any other folders or their contents. So it doesn’t download your sent items, your drafts, your deleted emails, and so on. Because it only downloads what’s in your inbox and it doesn’t do any kind of synchronization. So for example here we have two computers that are configured to retrieve the same email account. And as you can tell, the folder structures are different on these two computers because POP3 does not synchronize the folders.

Now by default when you’re using POP3, the email will be deleted on the mail server once it’s downloaded to a device. So no copy of the email is kept on the server. So what happens is, is when a new email comes into the mail server, if this computer up here checks the mail server first before this computer down here, this computer will receive the email but this other computer will not. Because the email has already been downloaded. So no copy of the email is kept on the server. However, most email clients will have a setting that you can check to leave a copy on the server so that all of your devices can retrieve the email.

Noe let’s talk about IMAP.  And IMAP stands for Internet message access protocol.  Now IMAP is also used for retrieving email but IMAP is a little bit different.  IMAP allows you to view your email that’s on the server from multiple devices.  The email is kept on the server and it caches local copies of the email onto all of your devices. 

, POP3 and IMAP Explained., TechRX

And it synchronizes all of your folders and everything that’s in them.  So it syncs your inbox, sent items, deleted items, drafts, and any custom folders that you may have created.  So when you view your email on your computer, tablet, or smartphone, your email would be exactly the same because everything is synchronized.

So for example in this demonstration we see that all the email and folders are exactly the same between these two computers.  So if we delete an email on this computer here, the email will be deleted on the mail server and then be deleted on this computer also.

So if we go to the other computer, and for example let’s go ahead and delete all the emails.  And when this happens, all the emails on the server and the other computer will be deleted also.  And if any new emails come in, the email first goes to the mail server, then as these computers sync with the mail server, the new email will appear on these computers.

So in another example let’s go ahead and make a custom folder.  So we’ll make a custom folder and then give it a name.  And because we’re using IMAP, the folder and all of its contents will be added and synced to the other computer also.  So every computer, tablet, and smartphone that you have, will have the exact same email and folder structure as the others.  So that’s how IMAP works.  

So as a comparison between POP3 and IMAP.  On the left we have POP3, and as you can see, the folder structure is different between these two email clients because POP3 only downloads the contents of your inbox folder.  It doesn’t do any email or folder syncing, so that’s why the emails and the folder structure are different.  But in IMAP everything is the same.  The email and folder structure are identical because IMAP syncs everything with all of your devices.  

Now both POP3 and IMAP are configured in your email client in the incoming server settings.  So for example if you’re using Gmail and you wanted to use POP3, you would type in your incoming server settings.  Or if you wanted to use IMAP, you would type

So the question is, which protocol do you actually want to use?  And that really depends on your situation.  Now POP3 is good if you’re only going to retrieve your email from one device.  The advantage of using POP3 is that since the email is downloaded to your device,  

you can view your downloaded email even if you don’t have an internet connection.  So the only time that you need an internet connection and POP3, is when you’re receiving new email or sending email.  Another advantage of POP3 is that it saves storage space on the mail server because the emails are deleted when they are downloaded to a device.  Now a disadvantage of POP3, is that since the emails are removed from the server and downloaded to your device, you would need a plan to backup your emails in case your device crashes or is lost.  And another disadvantage is that your  device has a better chance of being infected with viruses since the emails are fully downloaded.  

Now IMAP is good when you’re going to retrieve your email from multiple devices.  An advantage of using IMAP is that all the email is stored on the mail server.  So whether you’re accessing your email using an email client or webmail, you’ll be able to see all your email including your sent items, drafts, deleted items, and any custom folders.  And all the email and all  folders are all synchronized.  So every device that you have will see the exact same thing. 

Now a disadvantage of IMAP is that you will not be able to view your emails without an internet connection.  And this is because IMAP only caches local copies of the email on your device and doesn’t download them.  However, some email clients will give you an option that you can check to have IMAP download the emails to your device instead of just catching them.


  • , POP3 and IMAP Explained., TechRX

    My name is Biplab Das. I’m the leader of TechRX and Founder of and Professionally I'm a full-time IT support engineer whose childhood obsession with science fiction never quite faded. A quarter-century later, the technology that I coveted as a kid is woven into the fabric of everyday life. People say smartphones are boring these days, but I think everyone is beginning to take this wonderful technology marvel for granted.

Leave a Reply

Your email address will not be published.

Back to top button