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