What is email protocol?

It’s an everyday routine: you open up your email and watch the messages pop into your inbox. But behind the scenes, complex email protocols are hard at work to make things happen correctly. Email protocols are the technical procedures that define how your mail is stored, accessed, and managed, with two of the most popular options being POP3 and IMAP.

Emails are transported across the internet by mail servers, which receive and deliver messages from email client software like Microsoft 365 and Thunderbird, as well as browser-based webmail applications such as Gmail.

Most email clients can be configured to use POP3 or IMAP email, but if you’ve the choice, which one should you go for?

What is POP3 email?

POP3 email, or Post Office Protocol version 3, is the most common email protocol used for receiving emails via the web. It’s a standard email protocol that’s supported by almost every email server and client out there, pulling emails from a remote Dedicated Server before sending them to a local client.

Its key features include:

  • Only providing a connection when retrieving emails
  • Deleting emails from the server after retrieval
  • Allowing email retrievable only by a single client

How does POP3 work?

POP3 email works by establishing a connection between an email client and the POP3 remote mail server. It then downloads any messages to the client computer before terminating the connection. This ensures that only you will ever have access to your emails.

What is a POP3 server?

A POP3 email server is located in a remote location from the client, with layers of security to restrict access.

Typically, once you’ve downloaded your emails, they’re deleted from the server immediately after, and from then on are only stored locally on the client device – although POP3 can be configured to keep copies if you want it to.

More importantly, only one computer or device can connect to a POP3 email mailbox at any one time, and emails are usually only downloaded to a single client. Because mail is stored locally after it’s been retrieved from the server, it can be viewed and edited offline, without requiring a permanent internet connection.

What is IMAP email?

IMAP, or Internet Message Access Protocol, on the other hand, also establishes a connection between an email server and a client. Its main features include:

  • Hosting a permanent connection between the server and client
  • Retaining emails on the server until they’re manually deleted
  • Allowing email retrieval by multiple clients at the same time

How does IMAP work?

Unlike POP3 email, IMAP email maintains its connection with the server and client throughout the entirety of a user’s session, not just when emails have been retrieved.

On top of this, with IMAP email, all messages stay saved on the server even after retrieval by the client, remaining until the user decides to manually delete them.

This means that multiple computers or devices can connect to the same IMAP email inbox, and all have the same access to the same messages on the server, so long as an internet connection is available.

What is the difference between POP3 and IMAP?

When it comes to POP3 vs IMAP, your decision is really going to come down to how you personally choose to access your emails. Do you need to access the same emails on your office desktop as on your laptop when on the move? Or do you view your emails on a single computer and want your messages to be always locally stored?

Single machine access

Using POP3 email makes sense for individuals who like to access their emails from a single machine, with the added bonus of not needing a constant internet connection to access messages once they’ve been retrieved from the server.


POP3 email is also the simpler of the two email protocols, and because POP3 routinely deletes mail from the server, it’s generally less of a burden on resources - so much so that a Cloud Server is a perfectly viable option for email storage.

Even so, with storage relatively cheap and emails taking up relatively little space, there’s no real barrier to choosing IMAP over POP3 email.

Multiple devices

Naturally, if POP3 is better for single users, IMAP is better for users on multiple devices who need an equal level of access on their smartphone, tablet, or PC throughout the day.

Complex features

IMAP also offers more complex features than POP3, such as advanced options for managing folders, and status flagging of emails.

However, it’s worth noting that IMAP email does not store emails locally by default. Some clients will keep a few weeks’ worth of mail to be accessed offline, but these will be stripped of any images and attachments. With IMAP, there’s also the risk of being stuck without a connection and having no way to access previously retrieved emails.

But in our increasingly ‘always online’ personal and professional lives, where we rely on multiple devices on a daily basis, IMAP is generally regarded as the more relevant mail protocol out there. Connectivity is always improving, and the benefits of cloud computing mean that users can generally rely on enough online storage with a range of cloud backup options like in our Cyber Protect package.

Should you opt for POP3 or IMAP?

If you’re still not sure whether POP3 or IMAP is better for you, the good news is that it’s relatively simple to switch between the two on most email clients, meaning you can try both and see which works best.

If you’re looking for Email Hosting, we have a range of options for you to choose from. Our Exchange Email option is the ideal solution for email pros, and all our services support POP3 and IMAP email.

So whichever email protocol you settle on, you can take advantage of business-class features, flexibility and security, as well as outstanding 24/7 technical support. And for even more articles like this one, head over to the Fasthosts blog.