This article is to explain to unfamiliar customers the difference between POP3 and IMAP

As an email technician it's not uncommon to be asked to explain the difference between IMAP and POP. Let me explain...

IMAP and POP are two different methods that can be used to communicate with the mail server. If your account is set as a POP it will connect to the mail server, download all your messages and disconnect. The messages are now downloaded and stored locally on your computer. On the other hand, IMAP connects to the mail server and downloads just the subjects for each email ( this may vary from client to client). Only when you open the message does it download the rest of the email for you to view. While IMAP may use alot of data or connection time and sometimes slow the truth is, if you're computer crashed the messages would still be on the mail server. Sent folder, Trash, Inbox, Custom folders etc... would be waiting once you got the account setup again. POP is just the opposite. It isn't as connection intensive and it's alot faster because everything is local. It doesn't have to be continually refreshing your folders etc...

Another instance of where IMAP is handy is when syncing the same email account across multiple devices because what's sent from one device will also show in the sent folder on all the others.