1. Gmail’s system of organizing emails into conversations (a collection of all the messages in an exchange) makes it easy to keep track of the various messages in a discussion.
  2. You can access Gmail from a cellphone or other mobile device. Just start up your phone’s browser and point it to http://gmail.com to sign in.
  3. Although you can have periods in your Gmail address, Gmail doesn’t actually recognize periods—it treats the address exactly the same with or without the periods. So if your Gmail address is jesse.smith@gmail.com, emails sent to jessesmith@gmail.com or even j.e.s.s.e.s.m.i.t.h@gmail.com will reach you.
  4. If you’re reading an email and want to set up a filter for this message and similar ones, click More Actions and select “Filter messages like these”. (You can also select messages in a mailbox, and then choose this option.) Gmail shows the filter options with the sender’s From address already filled in. From there, you can filter by sender and/or any of the other filtering criteria.
  5. Gmail scans your emails, looks for keywords, and then pairs the email with advertising that relates to those keywords. Usually, one ad’s displayed above the message you’re reading and several others are on the right-hand side of the page (they’re easy to ignore). But Gmail tries to keep things tasteful, so if you receive an email about a tragedy, such as a death in the family, you won’t see any ads at all.
  6. You can set up your Gmail account so that messages sent to your other email accounts arrive in your Gmail inbox. That way, you can check all your email accounts in one place. Even better, in Gmail, you can send emails so that they look like they come from your various email accounts.
  7. If you write emails in more than one language, Gmail tries to guess the language of the email you’re working on and uses the appropriate dictionary. (If Gmail’s wrong, next to the Check Spelling link, click the arrow, and, from the list that appears, select the language you want.)
  8. You can chat with your AOL Instant Messenger buddies through Gmail’s version of Google Talk. In Gmail’s left-hand Chat section, click the Options link and select “Sign into AIM”, then follow the directions.
  9. To help protect you from viruses and other Internet threats, Gmail neither sends nor receives executable files—they typically have the file extension .exe—which can launch programs and wreak havoc on your computer.
  10. Instead of folders to file your messages in, Gmail uses labels to organize messages. You can assign more than one label to a message, so you have several ways of finding it and don’t have to remember which folder you put it in.

Source: Amazon.com, Google Apps: The Missing Manual