How Do I Send Mail From Another Address?

Step 1: Add an address you own

1. On your computer, open Gmail.
2. In the top right, click Settings   Settings.
3. Click the Accounts and import or Accounts tab.
4. In the "Send mail as" section, click Add another email address.
5. Enter your name and the address you want to send from.
6. Click Next Step  Send verification.
7. For school or work accounts, enter the SMTP server (for example, smtp.gmail.com or smtp.yourschool.edu) and the username and password on that account.
8. Click Add Account.

Step 2: Confirm the address

1. Sign in to the account you added.
2. Open the confirmation message you got from Gmail.
3. Click the link.

Step 3: Change the "From" address

1. In the message, click the "From" line.
   (If you don't see this, click the space next to the recipient's email.)
2. Select the address to send from.

For more information regarding this feature please look here.