To continue last weeks post about Rackspace Email. I decided today would be a good time to explain the nuances of IMAP and POP3. I will try and keep this as low-tech as I can. I wont define the protocols, as there is enough written about it on the web. I will explain it simply.

First, let’s set the stage. Imagine if you will that email is stored up the sky or cloud. We will pretend that all mail resides up there until you ask for it – by hitting send/receive.

Ok, now let’s knock out the older POP3 protocol.

Every time you check for email… Imagine a trapdoor in the sky opening up, and physically dumping all your emails into your computer or device. Since we are opening a door, its dropping into the machine… it means it is no longer up in the sky/cloud.

Now lets take the newer and much cooler IMAP protocol.

Every time you hit send/receive… Imagine a window shade opening, instead of having to physically download a piece of mail. The computer looks inside to see whats there. The mail is always and forever in the cloud. Your computer/device basically makes a copy of the messages and shows them in your email client. Next time it does a send and receive, it incrementally updates itself to show the new messages.

Why I like IMAP much better:

In todays world, we are not tied to one computer or device. We have cellphones, smartphones, iphones, ipods, ipads, tablets, laptops, netbooks and desktops. Often we have multiples of these devices. In this seemingly every growing connected world we live in, we want – no – we expect to be able to access mail on all our devices.

If we were to setup POP3 on each device, they would fight for the physical piece of mail. Devices would constantly struggle to keep in sync. Fighting over the one message. Maybe it ends up on your phone. Then later you check your PC, and its not in your desktops email client (remember it’s on your phone). Give up trying so hard to keep this in sync. Use IMAP.

In my life I check email on my iPhone, iPad, Laptop and iMac. Sometimes I also check via the web. Since all of my devices are setup using the IMAP protocol. Everything is ALWAYS in sync, without the need of jumping through insane hoops. It just works.

Two caveats that I like to mention in helping with IMAP.

1. If you do something to an email message on a device, it will replicate that “something” on the other devices. For example… If you delete the message on your phone. The message really deletes on all devices – as well as the server. If you file the message in a folder called “vendors” on your desktop, it will move to that same folder an all other devices.

2. Each time your device does a send and receive, it is indexing what is on the server and syncing changes. I find it helpful to keep your inbox clean. Meaning keep a minimal amount of messages in there at a time. Once you are done, file it, delete it, whatever.

If you are the type that likes to keep 20,000 emails in your inbox. You are asking for trouble. Remember each of those devices has to count and sync all those messages a great many times a day. My email client checks every two or three minutes. Imagine if it had to count to 20,000 each time it checked for mail, and file/delete/move/sync as needed. That can cause hiccups.

Hope that demystifies POP3 and IMAP.