By default, Gmail gives you the option of only attaching images to an email. However, with this feature enabled you can embed images from your computer or from a website directly into the mail body. Go to Settings, click on Labs, scroll down to the feature that says "Inserting Images" and enable it. You will notice the new insert image box in your mail composer right next to the emoticon icon.
2) Stop that mail
Pressed the send mail button too quickly? Gmail Labs has a feature that gives you a few seconds to stop the mail from going out after you press the send button. Go to Settings, click on Labs and enable the option that says "Undo Send". Click General under Settings and here you can select the time (up to 30 seconds) for which the email can be stopped after it is sent. When you press the send button and the inbox comes up, you would see a yellow box saying, "Your message has been sent. Undo or View message" on top. Click on undo to cancel sending the mail and get the draft back. You can then make the necessary changes to the text or add the recipients you forgot and send again.
3) Sharing your power
This feature is useful for people who have multiple Gmail address or who want to grant read/write permission for their account to another user. Go to Settings, click on Accounts and Import, at the bottom you will see an option that says "Grant Access to your account". Click on Add Account and enter the Gmail address of the person you want to grant access. Once the person accepts the verification mail, he/she can access your account by clicking on the arrow next to his own mail ID on top right and selecting your mail ID. The access allows the user to read, write and delete mails.
4) Reply to all
Gmail's default reply button composes the mail to the person who has sent the mail ignoring all the people who were put in CC. If you have to do a reply all, you have to press the arrow next to the reply box and then select "reply to all". Instead, you can set the "reply to all" function as default. Go to Settings, click on Labs and enable "Default reply to all" feature. It is far simpler to just remove selective email IDs from the CC box than selecting " reply to all" from a drop down box every time.
While communicating with friends, family or colleagues in different parts of the world, we sometimes forget about time zones. While it is mid-afternoon for you, it might be midnight for the recipient and hence an immediate reply will not come. To know the difference in time zones for both parties, enable the "Sender Time Zone" feature by going to Settings and clicking on Labs. Now, when you click on "show details" in the mail, you can see the time at which you have sent the mail and what time is at the receiver's end and vice versa.
Sometimes, you want to just have a quick look at the mail without opening the whole conversation. Gmail Labs enables you to do this with a simple tweak. Go to Settings, click on Labs and enable the "Message Sneak Peak" feature. Now, when you right click on any mail from the inbox, it will show you the latest mail received or sent in the conversation along with options to delete or mark as read, you don't have to open the entire conversation.
7) Control the content
You've probably noticed those little one, line ads that keep rotating on the top of the inbox above the various buttons. Not only are they unobtrusive, but also they can be rather helpful, sometimes offering relevant information. Those ads are called Web-Clips and Gmail gives you the option to select what kind of content you want to see there. Go to Settings, click on Web-Clips and here you can remove all the topics that Gmail has added by default. Instead add the topics that you want to read about from the available selection. You can also add the RSS feed of your favorite website by entering it in the search box on the left and adding the feed.
8) Next in line
While checking your mail or going through results of searched mail, when you delete or achieve a conversation, Gmail takes you back to the inbox or search results listing. Wouldn't it be great if instead of going back to the listing, Gmail would open the next or previous mail? Go to Settings, click on Labs and enable the "Auto-Advance" feature. Now click on General and there select if you would like Gmail to take you to the next mail, previous mail or back to the listing interface when you delete or archive a mail. Depending on your preferences, this could save you a lot of time in navigation.
9) My mail, my shortcuts
Although Gmail offers a lot of features, it doesn't offer everything for everybody. However, if you enable the "Add any gadget by URL" feature under Settings > Labs, it opens a whole new dimension for adding what you need to your sidebar. Once enabled, go to Settings and click on "Gadgets". Here in the box that says add a gadget by its URL, simply search for a gadget on Google that suits your need and add it. There are already a bunch of gadgets available that integrate various social network feeds on sidebar as well as add functionality such as reminders, URL shorter etc.
Note: Whenever you enable any of these features, Gmail reloads to show the new controls and add-ons.