Google announced that Gmail users can send now email using other SMTP servers without ‘on behalf of’ appearing in From header.
We heard your request for another option that wouldn’t show the "on behalf of" text loud and clear, and now there’s a new option that does just that. Instead of using Gmail’s servers to send the message, we’ll use the servers where your other email address lives. Since Gmail isn’t the originating domain, we don’t have to include "Sender" info in the header. No more "on behalf of."