Gmail Help Center Guru, Sze-jun Tsai has posted a very useful post on the Gmail Blog about configuring your Gmail account on mobile devices using IMAP rather than POP.

Sze-jun mentions how frustrating POP can be due to it's limitation to communicate only one way rather than 2 way like IMAP. Sze-jun also provides a simple graphic which explains the benefit of IMAP over POP.

There are two ways your devices and clients can communicate with Gmail:

A one-way communication path (POP). Your device asks us for data and pulls it from our servers -- but that's it. Things you do on your device have no effect on the server. If you read a message on your phone, then log in to Gmail, you will see that same message marked as unread. It may start to feel like Groundhog Day.

A two-way communication path (IMAP). Unlike with POP, your devices talk back to our servers and sync your changes automatically with IMAP. When you sign in to your Gmail account in a web browser, actions you've taken on your email client or mobile device (like putting a message in a 'work' folder) will also appear in Gmail (your message will already have a 'work' label on it). This all happens automatically once you set up IMAP, so you don't have to read or sort all your mail twice. This is really helpful when accessing Gmail from multiple devices.

1. Sign in to Gmail.
2. Click Settings at the top of any Gmail page.
3. Click Forwarding and POP/IMAP.
4. Select Enable IMAP.
5. Configure your IMAP client and click Save Changes.

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