Unable to add .msg type in Accepted MIME Types in the upload button in Web designer portal

Hi All,

I have an upload button which is present in the front end web designer portal (v 9.2.1)

The customer gave a list of acceptable MIME types which is currently present. Customer also wants to upload file of type .msg (Outlook message files)

I tried using application/vnd.ms-outlook , and is not working.

Any suggestion as this is in production and became a top priority issue right now.

Thanks in Advance