I think you can do this when you pre-authorize the address you want to send
the mail as. Meaning you have to log into your contactus gmail account and
authorize a specific email address as authorized to send-on-behalf-of (this
requires an email sent to that address to authorize the action). Of
In Gmail you can forward messages with a filter. The receiver of this
relayed messages does not see any difference. The sender is the
original sender. In the “delivered-to” field of the message header
you can find the relay mail address.
I tried to build the same functionality with GAE.
