POP and IMAP Explained

20th August, 2014 by

Neil Cumins explains what POP and IMAP are, the difference between them, and how to pick the right one when setting up your emails…

If you’ve ever tried to configure an email account, you’ll be aware of the acronyms POP and IMAP. Created in the mid-1980s, these either/or terms represent two very different ways of managing messages before they are received. They are not email packages in themselves, but they do govern how message data is received and stored. The choice between them depends on your individual requirements, although IMAP increasingly resembles VHS compared to POP’s Betamax.

The time-honoured Post Office Protocol, now in its POP3 version, pulls a single copy of each message directly from the sender to the recipient device. Although it will always be visible on that device (even when there’s no Internet connection) the message can’t subsequently be duplicated or viewed anywhere else. Users with a POP account should periodically back up their data files, to prevent this one-time information being irrevocably destroyed by a virus or natural disaster.

Internet Message Access Protocol, meanwhile, hosts new messages on a cloud server, before temporarily displaying it on any device that provides authenticated login credentials. Emails can be accessed from pretty much any Internet-connected device anywhere in the world – as long as you can remember your username and password. A message drafted on your smartphone will be visible on your iPad, and can be sent later from your desktop PC. There’s no need to routinely back up data, since it’s already stored offline and any changes are instantly logged on the host server. This is also a quick system, since only email header information is typically displayed until further content is requested.

As is often the way, the choice between protocols isn’t as clear-cut as it initially appears. POP systems can store copies of messages on central servers even after downloading them, although logging in from elsewhere may reveal a swathe of previously-viewed messages all highlighted as unread. Meanwhile, IMAP demands a steady Internet connection to achieve pretty much anything. Assuming the person or organisation configuring your email gives you a choice (which many don’t), the decision between POP and IMAP effectively boils down to how you access your data. People with a desktop PC in their home office can quite happily use POP, while anyone who wants mail on the move should select IMAP.

Determining which system your existing email account is configured to depends on the device and software you’re using. In Microsoft Outlook 2010, for instance, clicking the File tab will display a box below the Account Information header that will identify your method of connection.

It used to be the case that IMAP servers could become clogged with messages and grind to a halt, but then Outlook PST files frequently corrupted once they reached 2GB in size. The world has moved on since then. With webmail accounts like Yahoo now offering one terabyte of storage, you’d have to amass roughly 54 million emails before you began stretching the limits of cloud storage. Gmail even allows you to switch between POP and IMAP at any given time, for added flexibility.

To find out more about setting up emails with UK2 visit our knowledge base.

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