Display New Message Form and Add Base 64 Document

I'd like to request an update to displayNewMesageForm to be able to send one or multiple files to attach to the new message from a Base 64 string.

The current process of having to provide a URL that is unprotected does not work in corporate environments where files need to be secure, nor can I get attach addFileAttachmentFromBase64 as there is no way to get the new message form as the current mail item.