As if Gmail wasn't powerful enough, you can find all sorts of goodies and extra features in Gmail Labs. The list is pretty massive, so we've narrowed down our 10 favourite labs to help increase your email productivity.
We've actually gone through our 10 favourite labs before, back when Labs was a bit younger. Now, many of those features are part of Gmail itself, so we've decided to revisit the labs and see what else Gmail has cooked up. To access these features in Gmail, just hit the green flask icon next to "Settings" in the Gmail web interface.
10. Undo Send
We've all been there: you spend half an hour writing a strongly worded letter, hit send, and realise you probably shouldn't have done that. Thankfully, Gmail Labs' Undo Send feature is there to save you from yourself. After sending an email, Gmail will wait a predefined number of seconds (5, 10, 20, or 30, configurable in Gmail's settings) before sending—at any point during which you can hit the "undo" button to take back your mistake. Even if you don't foresee needing it, it's a heck of a lot better than yanking out your Ethernet cable, so you might as well keep it around just in case.
9. Advanced IMAP Controls
If you like Gmail but use a separate mail client like Thunderbird or Mail.app to access it, you've probably had a bit of confusion with Gmail's IMAP implementation. Labels are now folders, some folders you didn't even know existed, and there are multiple copies of messages everywhere. If you access Gmail via IMAP, you'll definitely want to enable Advanced IMAP controls, which let you select which labels actually show up in your mail client. Once enabled, you can access its settings from the Labels tab of Gmail's settings. Even if you don't regularly use a mail client to get your mail, it's pretty useful to have it ready when Gmail goes down for awhile.
8. Inserting Images
Sometimes, plain text just doesn't get across everything you need to in an email. In those situations, the Inserting Images lab will help you out by letting you insert images easily—whether you upload them from your computer or link to an external source on the net—with the press of a button. Note that if you're running Google Chrome or Safari, you don't need this lab enabled—you can just drag and drop images right into the Gmail window instead.
7. Default 'Reply to All'
This one's a simple lab, but a Godsend for us scatterbrains out there. Often, when multiple people are involved in an email thread, one person will break off by accidentally hitting the "Reply" button instead of "Reply All", and then everyone else misses that part of the conversation. Save yourself from being "that guy" by enabling the Default Reply to All Lab, which changes Gmail's Reply button into a Reply All button. On the occasions you want to reply just to one person, you'll still be able to do so by hitting the dropdown menu next to the Reply All button.
6. Canned Responses
If you find yourself doing a lot of repetitive typing, the Canned Responses lab will save you a lot of trouble. Just enable the lab, set up those messages you find yourself sending over and over again, and then send them with the click of a button. You can even send them automatically using filters and use them with external services (like automating Remember the Milk tasks). Note also that you can use OS-wide text expansion if you need to do this outside of Gmail—though what's nice about Gmail's canned responses is that you can use them no matter what computer you're on.
5. Google Docs Previews
Even if you aren't the biggest fan of Google Docs, the Google Docs previews Lab is pretty useful—it not only lets you preview shared Google Docs, but it also lets you view any Google Docs compatible format before downloading it. That means the next time someone sends you a Word document, Excel spreadsheet, or PDF and you don't want to download it and open it up in Office, you can see what's inside just by viewing its Google Docs preview.
4. Custom Keyboard Shortcuts
We love keyboard shortcuts. It's no secret. The shortcuts in Gmail are some of our favourites, allowing you to ninja your way through Gmail with just your keyboard—and they even add a few every once in a while. That said, if you don't find Gmail's default keybindings very intuitive, the Custom Keyboard Shortcuts lab lets you make your own from Gmail's Settings page.
3. Quick Links
While features like starred messages and Multiple Inboxes are great for accessing oft-needed labels or messages, Quick Links is great in that it stays mostly out of your way. Quick Links adds a small box to Gmail's sidebar, in which you can add one-click access to any bookmarkable URL in Gmail—like saved searches, specific messages, labels, or anything else. You can just use them as a handy grab bag of links, or even turn them into a killer to-do list.
2. Message Sneak Peek
The Message Sneak Peek feature is simple, but pretty useful—instead of opening up every message you get, you can just mouse over them to see what's inside a message. That way, you don't have to go through to trouble of opening it, marking it as unread, or filtering it if you can't deal with it right away. If you want a bigger sneak peek at your messages, you can use this customised stylesheet to add a scrollbar to the feature.
1. Multiple Inboxes
This is still one of our favourite Gmail features here at Lifehacker—there's just so much you can do with it. Whether you want to turn Gmail into your ultimate GTD inbox, use Gmail as your central, universal communications hub, or just manage multiple addresses, Multiple Inboxes has you covered by letting you stack extra lists of emails—whether they be labels, starred messages, or any other Gmail search—in your main inbox window. There's no limit to what you can do with Multiple Inboxes, so if you've ever felt anything was missing from Gmail's inbox organisation, you can make it yourself here. Note that, unfortunately, Multiple Inboxes does not currently work with Gmail's Priority Inbox feature, so you'll have to decide which is more important to you for a particular account.
There you have it—ten of our favourite Gmail labs for increasing productivity. These are all great for managing your email, but we all know Gmail Labs can help you do so much more—like act as your central, universal communications hub and video chat in higher definition. So while you're checking out our favourite Labs, check out the others available too, because there are some other great ones. And if you have a favourite that we didn't share, let us know about it in the comments.