If you are forwarding your branded emails to gmail you can reply as the branded email when it arrives there.  This is a simple process as described in these steps.

  1. Click on the wheel icon upper right of Gmail
  2. Select "Settings" to open the account settings
  3. Click on the Accounts tab
  4. In the "Send mail as:", click Add another email address
  5. When the yellow box pops up for "Add another email address you own", Enter the name and email address (myname, myname@mydomain).
  6. Click the Next Step button
  7. SMTP server leave as smtp.gmail.com
  8. Username: (your gmail email)
  9. Password: (the password you use to log into gmail)
  10. Leave Secured connection using TLS checked
  11. Click Add Account
  12. You may need to turn on Allow for less secure apps if you get blocked.  Follow the link.