What's the difference between POP / IMAP

The fundamental difference between IMAP and POP is how messages are transferred, and how long email is stored on the mail server.

When POP is used, messages are "pulled down" from the mail server, and depending on how you have set up your email software, they may or may not be deleted from the server during this process, or following it. Typically, messages are removed from the server either immediately, or after a given time period such as 10 days, once the message has been "POPed" to your email software. 

This means your emails are accessible only from the individual computer or device to which they have been downloaded (unless you have specifically set up each device's email program to "leave a copy of the email on the server"). In this regard, if the computer or device that has downloaded all of you email decides to go the way of the dinosaurs, or worse - is stolen, all of your historical emails will be gone - unless of course you have made file backups - which of course you have, haven't you?!!!

While POP conserves your hosting server’s disk resources (less space taken up with saved, old emails which are being downloaded instead), it generally limits how you can access your email. One advantage to note however, is that unlike IMAP, POP does not require a constant connection to the email server while email is being read (useful if you are offline much of the time and only go online to send/receive emails).

When IMAP is used, messages are generally stored permanently on the mail server, but the "header" and "content" of messages are transmitted to email clients (e.g. your phone, your desktop email software such as Outlook, or your smart TV!). This means that they can be accessed by any number of computers or devices as long as the user has the correct login information. In other words, all of your devices - e.g. your desktop, your tablet, your phone - that are connected via IMAP to the email server - will "mirror" the other in terms of your email.  In this respect, if you delete a message on your computer email software for example, it will also be deleted from your phone and the server and visa versa etc.

IMAP is generally considered quite convenient since you can access the same inbox or outbox from multiple devices.  However, IMAP generally requires more dedicated disk space because messages are not being actually downloaded or deleted in the same manner as they are in a typical POP scenario. Therefore, IMAP is great, so long as users monitor their disk usage and continues to delete old are unwanted messages when necessary. It may also be important to note that IMAP requires a constant connection to the email server while email is being read - so it is not suitable for users that frequently go offline for long periods.

The Best Solution?
Use POP AND IMAP by sending and receiving your email via our servers, but through Gmail or Google Apps.  With this solution, you will never need to delete old emails!  Click here to find out how to set this up.


  1. SMTP: SMTP (Simple Mail Transfer Protocol) is a set of standard Internet procedures by which two email providers (example. Gmail, Yahoo Mail), transfer email messages to one another’s mail servers.
  2. Domain: A domain is a name for an IP address and is more commonly recognized as a website or web address. For example, Google.com is a domain.
  3. SSL: SSL (secure socket layer) is a way of changing data such as your username and password into code as it travels across the Internet, so that the data will be secure and private.  An SSL certificate must be installed on the server in order to protect a website with HTTPS and indicate a secure site.
  4. ISP: An ISP (Internet Service Provider) is a company (ex. AOL, AT&T, and Comcast) that gives your computer Internet access. ISPs are usually the companies that come to your house and set up all the wires.
  5. TLS: TLS (Transport Layer Security) is a way of changing data such as your username and password into code as it travels across the Internet, so that the data will be secure and private. With mail delivery, TLS begins with an unsecured connection to the mail servers, and then upgrades to a secure connection once information is sent.
  6. POP: POP (Post office protocol) is a one-way download of your messages that allows you to access your mail with a mail program like Outlook Express or Apple Mail. POP only offers one-way communication, which means that actions you take in the mail program (like marking a message as read) won’t be synced to Gmail.  In addition, if you choose not to keep a copy on the server, all of your email would be lost if your computer malfunctioned, since it is stored locally.  We recommend regular backups AND IMAP instead!
  7. IMAP: IMAP (Internet message access protocol) lets you download messages from the Purple Dog Server (or Gmail if you are using that service) so you can access your mail with a program like Outlook Express, Apple Mail or Thunderbird. IMAP syncs the actions you take in your email client with the server so if you read a message in your mail client, it'll be marked as read on the server (or in Gmail).  Also, if your computer malfunctions, your email still exists on the server, so long as you haven't deleted it.  Furthermore, you can access your email from a wide range of devices, all using IMAP and all reflecting the same message status (e.g. read, junk, sent)
  8. GMail: Gmail is a free web based email utility provided by Google.  Although a third party product not related to Purple Dog, we recommend using Gmail in conjunction with IMAP on your local machine for best email results.  It can be a bit complicated to set up - but once its done, you shouldn't ever have to worry about email set up issues again (unless you change computers)


If you are having difficulty deciding what email service to use, just let us know via a support ticket and we can help you decide.


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