When sending emails from Gmail through any alternate email address (xyz@abc.com) other than the default email address (lmn@gmail.com), the annoying "on behalf of" words is added next to the email address.
The way to get rid of that is to use a SMTP server from other webhosting companies (settings -> Account and Import -> Send mail as -> edit info). Unfortunately, Gmail allows only SMTP server with TLS support. VPS packages from IxWebhosting support this feature.