If you use Gmail's Mail Fetcher tool to grab email from other POP3-enabled email accounts, you may have noticed that it sometimes checks for new mail on very slow intervals—particularly if you're importing from a mostly inactive account.

The following post was originally published in Chapter 1 of our new book, Upgrade Your Life: The Lifehacker Guide to Working Smarter, Faster, Better. You've finally decided to move all your email online to Google's web-based service, Gmail. Great! But what about messages still going to your old email address(es)? You don't have to notify all your contacts that your email address has changed—again. Gmail is not only an email host, it's an email client, which can fetch mail from any number of external services and consolidate it all right there in your Gmail inbox. Here's how to move your email to Gmail without missing a single message from an existing account.

All platforms: Normally we don't feature individual widgets that require downloading a separate engine to run them, but the Informer Yahoo Widget might be worth the effort. Place system monitoring tools right on your desktop with Informer, like Wi-Fi signal strength, system uptime, and disk use. Keep tabs on your favourite web site feeds and inboxes with RSS and email notifications for Yahoo Mail, Gmail, and any other POP or IMAP account. Add shortcuts to local folders, favourite web sites and images as well with Informer. Check out Cybernet News' walkthrough of what you can do with this full-featured widget, which is a free download for Mac or Windows and requires the Yahoo Widget Engine to run.

Informer

If you've finally succumbed to the email tractor beam that is Gmail but still have email sitting around in other accounts, it's not hard to suck in those old messages into your Gmail archive. The Official Gmail blog runs down how. In short, you're setting up Gmail's POP mail fetcher to grab messages from your old accounts, with a little automatic label-and-archive action thrown in for good measure. Tips for importing old email to Gmail

Firefox only: Somewhere between web-based email and a standalone desktop client there's Simple Mail, a Firefox extension that embeds an email client right inside a Firefox tab. Manage all your messages in Simple Mail, which can notify you of new incoming messages at a rate you define for any number of POP or IMAP email accounts. Simple Mail lists your messages in a familiar three-paned view where you can read, compose, and send messages, as well as maintain an address book. I had trouble getting Simple Mail to work with Gmail and IMAP in Firefox 3 on the Mac, but all went well in Firefox 2/Windows, so Mac users, proceed with caution. Simple Mail is missing features you'd expect in a full-blown client—in fact, I couldn't get it to see the folders on Gmail's IMAP server. However, it does give you that desktop feel without having to run or switch to a separate application. Simple Mail is a free download for Firefox only. Thanks, Masa! Simple Mail

A Lifehacker reader in the Army reserves says the military is transitioning from POP to IMAP email access, so he wants to know how he can continue to use Gmail instead of the Army's limited-space solution. Support our troops! Get the full story after the jump and offer up any solutions you might have for getting IMAP mail into Gmail.