Google Apps allows the ability to send messages using other email addresses you have listed as the sender instead of your primary address. To configure this you will need to already own the email account linked to the alternate address.
- Sign in to your Google Apps email account.
- Click the menu in the upper-right and select Settings.
- Select the Accounts tab.
- Under Send mail as, choose Add another email address.
- Enter your name and alternate email address.
- Click Next Step.
- Click Send Verification. Google will send a verification message to your other email address to confirm that you own it.
- Click the link contained in the verification email or enter the confirmation code in the Accounts section of your Google Apps email settings.
Messages sent will appear to be from the domain alias or email alias.
Please be aware that the return-path of the message received by the recipient will show your primary mail addresses in original message header.