Yesterday Google announced the rollout of free IMAP4 over SSL access for GMail. This allows you to keep your Gmail message state information such as whether or not a message has been read, replied to, or deleted synchronized across any IMAP4 client on desktop or mobile device such as Nokia S60, Windows Mobile, Windows Mail Desktop, iPhone, Sony Ericsson UIQ, Blackberry, Outlook 2003/2007, Thunderbird and Mac since these flags are stored on the server unlike POP3.

Here are a few resources to setup and configure IMAP4 over SSL for a multitude of desktop and mobile clients:

+ Nokia S60
+ Sony Ericsson UIQ3. This tutorial points to a help guide from Synchronica. Just substitute Synchronica’s server names with Google GMail’s IMAP server.
+ Blackberry
+ Apple iPhone
+ Motorola Razr (Note: External guide, similiar to Sony Ericsson above)
+ Windows Mobile
+ Outlook 2003
+ Outlook 2007
+ Thunderbird
+ Windows Mail Desktop
+ Outlook Express
+ Mac Apple Mail

To enable IMAP in your GMail account, goto your Settings, Forwarding and POP/IMAP and select Enable IMAP.
Tip: If you don’t see an IMAP option yet, change your language/locale settings to US English and sign in again.