Many people have not heard the term IMAP before, or do not know why it’s better than POP for email.
The easiest way to understand IMAP is to think of webmail. When you use webmail, you manipulate (reply, delete) messages directly on the server. When you use POP mail, you download each message to your local computer first, then manipulate it.
If you have more than one computer, and you POP down your email, the message may no longer be waiting for you on the server when you check from a second computer, unless you specifically configure your mail client to leave older mail in place. This is a configuration hassle, and also has a tendency to leave desktop mail and webmail out of sync.
When you configure your mail client to use IMAP, it works basically like webmail — you manipulate mail directly on the server, but with the superior control of a desktop mail client. Because you’re working directly on the server, your desktop mail and your webmail stay in sync automatically. Most modern mail applications can do both POP and IMAP.
So if you keep a lot of old mail around, what about your mail quota? Won’t you run out of mail space on the server? When you create new mail folders in most desktop IMAP clients, they’re created locally on your computer, unless you specify otherwise. So when you save a message into a folder for posterity, it’s moved off the server and into your local mail store. So you’ll have folders on the server for your Inbox, Trash, Sent Mail, and maybe a few others, while your permanent store of archived mail will live on your computer.
Setting Up IMAP
All mail clients will ask whether you want to create an IMAP or POP account when configuring a new mail account. If you’re already a POP user and want to convert to IMAP, note that not all mail clients allow you to convert easily – you may need to create a new IMAP account, then rename and disable the old POP account.
Regardless whether you’re creating a new IMAP account or converting an old POP account, there’s one step you’ll need to take to make your mail client behave properly – set the “root” folder or “IMAP path prefix” to
INBOX. You’ll find this setting somewhere in your client’s options or preferences for the account. In Apple Mail, you’ll find it in the Advanced section – it looks like this:
Other mail clients look different, but will have a similarly named folder. Here is Apple’s official knowledgebase article on the subject.