IMAP vs POP: What is It and Which Should You Use?

IMAP and POP are the two ways an email programme collects mail from a server. IMAP leaves your mail on the server and keeps every device in sync with it. POP downloads mail to one device and, by default, deletes it from the server afterwards. If you read email on more than one device, you want IMAP.

That is the short answer, and the POP vs IMAP decision really does come down to that one question. The rest of this explains what each one is doing, what the trade-offs actually are, and how to set either of them up.

What is IMAP?

IMAP stands for Internet Message Access Protocol. Your mail stays on the server and your email programme shows you a view of it. Open a message on your phone and it is marked read on your laptop too, because both are looking at the same mailbox rather than holding their own copy.

A rough sequence of what an IMAP client does when you open it:

• Connects to the mail server.
• Fetches what you have asked to see, such as a list of new mail, message headers, or the body of whichever message you clicked.
• Sends your changes back, so marking something read or moving it to a folder happens on the server.
• Disconnects.

Folders work the same way. Make one on your phone and it appears in webmail and on your laptop, because the folder is on the server rather than in one programme.

What is POP?

POP stands for Post Office Protocol, and the version everyone means is POP3. It was designed for a world where you dialled up, pulled your mail down, and hung up. The client connects, downloads everything new, and then removes it from the server.

• Connects to the mail server.
• Downloads a copy of the new mail.
• Stores it on that device.
• Deletes it from the server, unless you have ticked the option to leave a copy.
• Disconnects.

That last point catches people out. Most email programmes have a leave a copy on the server setting, and whether it is on by default varies by programme. If it is off and you set up POP on a second device, that device gets whatever arrived since the first one last checked and nothing else.

The difference between IMAP and POP

The single difference everything else follows from: IMAP treats the server as where your mail lives, and POP treats it as a collection point you empty.

So with IMAP, your mail is wherever you are, and it is still on the server if a laptop is stolen or a phone goes in a puddle. Your mailbox counts against your hosting storage, and you need a connection to read anything you have not already cached.

With POP, your mail is on one machine. It is fast, it works on a train with no signal, and it uses almost no server space. It is also the only copy you have, so it lives or dies with that device and whatever backup you run on it.

Should you use IMAP or POP?

For almost everyone now, IMAP. Storage is cheap, most people read email on a phone and a computer, and having your mail on a server that gets backed up is worth more than the disk space it uses.

Choose IMAP if:

• You read email on more than one device, which includes reading it in webmail occasionally.
• You want a message you filed on your laptop to be filed on your phone too.
• You would rather your mail survived the device it was read on.

Choose POP if:

• One device collects the mail and nothing else ever will.
• You need years of archived mail available with no connection at all.
• You are working to a hard mailbox quota and cannot raise it.

If you are torn, use IMAP. The case for POP is narrow and specific, and if none of those three lines describes you then it does not apply.

IMAP, POP and SMTP port numbers

These are the standard ports. Use the encrypted ones. The plain-text versions still exist and still work, which is exactly the problem with them.

Port 25 is blocked on most home and mobile networks because of the volume of spam that used to come out of it, so if sending fails and receiving works, the send port is the first thing to check.

Setting up IMAP or POP on your hosting

Every Snappyhost plan comes with unlimited mailboxes on your domain, with IMAP, SMTP and webmail included on the same account as the site. You do not pay per mailbox and you do not need a separate email product.

In cPanel, go to Email Accounts, find the address, and click Connect Devices. That page lists the exact server name, ports and username for both IMAP and POP, so you can copy them into Outlook, Apple Mail or your phone rather than guessing. The username is the full email address, not the part before the at sign, which is the single most common reason a setup fails.

If you would rather not set anything up at all, webmail reaches the same mailbox from a browser and behaves like IMAP, because it is reading the server directly.

Can you switch from POP to IMAP?

Yes, and it is worth doing if you are still on POP for no particular reason. The thing to be careful about is the mail already sitting on the device, because the server has not got it.

The safe order is: add the account again as IMAP alongside the existing POP account rather than converting it, then drag the old local mail into the new IMAP folders so it uploads to the server. Once you can see all of it in webmail, remove the POP account. Doing it the other way round, by deleting the POP account first, is how people lose ten years of email.

On a large mailbox that upload is not instant and it is worth leaving it running. If you are moving to us from another host, our migration covers mail as well as the site, so this is something we can just do for you.