There should be a way to quickly transfer an activity (usually email) attachement from the Timeline to the Documents library (SharePoint integration). Two ideas:

1. Via Assistant : Suggested documents. Assistant suggests adding a document in an email to the Document library. Accepting the suggestion transfers the file to the document library.
2. Via Quick Action : Icon is added next to document name. Clicking on icon transfers document to Document library.

At present, the process is very cumbersome. The document must be downloaded locally and then re-uploaded into the document library.