[Outlook] Create message API with MIME mail as payload

Question

Hi,
we are currently developing an Outlook addin with OfficeJS, with which a user can encrypt/decrypt emails via an Identity-Based Encryption scheme.
One of our user stories is that after decryption a copy of the decrypted mail should be stored in a folder within the mailbox of the user, and another story that a copy of the plain mail is stored for the sender such that she/he can search back the information.

However, currently I can only create emails via create message of the Graph API by providing the email as JSON payload.
But this email is then stored as draft, and is confusing for users if they see the mail as draft.
Wouldn't it be possible to accept - similar to the send message API - that the payload can be in MIME format, and subsequently, the mail is stored as is?