Only documents of type SCR or RAW can be faxed

What causes this issue?

Only documents of the type SCR or RAW can be forwarded to a fax
address. Any attachments which exist are not forwarded.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Please select the field <LS>Also place in inbox</> so that no documents
are lost.

Error message extract from SAP system. Copyright SAP SE.