Configuring GMAIL to send email as an alias
Gmail lets you send messages with another of your email addresses listed as the sender instead of your Gmail address. This feature helps you manage multiple accounts from the Gmail interface; it works only if you already own the email account linked to the alternate address. To send mail from a different Gmail username, you'll first need to sign up for that address. Select an option below for instructions on how to add your other addresses to your Gmail account.
I'm a Gmail or Google Apps user sending from an external address.
1. Sign in to Gmail.
2. Click the gear icon in the upper-right, select Settings and select the Accounts and Import tab (or Accounts tab, if you're using Google Apps).
3. Under Send mail as, click Add another email address.
4. In the 'Email address' field, enter your name and alternate email address.
Leave the check box in Treat as an alias.
5. Choose one of two options:
o Use Gmail's servers to send your mail (this is easier to set up) (use this option)
6. Click Next Step >> and then click Send Verification. Gmail will send a verification message to your other email address to confirm that you own it.
7. Open your other account and either click the link in the message Gmail sent or enter theconfirmation code in the Accounts section of your Gmail settings.
If Gmail sends a verification email and you didn't receive the it, the message was probably caught by a spam or bulk mail filter in your recovery email system. Try checking your Spam or Bulk Mail folders for a message from firstname.lastname@example.org to see if the email ended up in there.
8. Now change this to your default Send mail as:
That’s it now every email you send out will be from this address.
For more information from Google click here.