1) Login to the HELM control panel.
2) Click on “Domain” or search the domain.
3) Select the domain.
4) Go to the icon “MIME types”.
5) Click on “Add New”.
6) Enter the extension of the file that you wish to add to your domain.
7) Enter the description of that file type in Content Type heading.
8) Click on save.
Now on, the file containing this extension will be accepted by the server for this domain.