You could choose an email address from your domain to send emails out of Freshdesk. You could add this new support email by navigating to Admin > Channels > Email > New Support Email.

Furthermore, if you wish to remove the Via tag in your emails, you could either add a DKIM record in your domain or use a Custom Mail-Server along with your Freshdesk Account.

Note: If you have subscribed to the current plans, the Custom Mail Server feature can be accessed through the Growth plan. Alternatively, if you have subscribed to previous plans of Freshdesk, the feature is available through the Blossom plan.