Paul de Jong thanks for the detailed and informative reply.
> no support for metadata extraction (e.g. subject, sent date, ...)
This is indeed a major oversight. I'm looking at a macro/flow solution which files away an email from Outlook into SharePoint, and which at the same time populates some custom fields (columns) in SharePoint with some additional metadata... including some pretty basic ones like To and From, which IMHO should not be necessary. This is 2023 and these applications are all within the MS ecosystem so it really should be a thing already.
> the need to download emails to the local computer increased the compliance / security risks
Yes. It would be so straightforward to implement (at the bare minimum) the ability to open the .msg file into native Outlook at the click of a button (or from a context menu), like you can with Word documents from SharePoint. It's one of the lowest hanging fruit possible in this context, surely?
> here are quite some organizations that want to store emails in SharePoint together with
> the related project/client data and keep relevant information together and have a
> single source of truth
Exactly this! We have a whole range of documents and document types, including emails, pdfs, Word, Excel and so on, and we want to keep them all in the same place, so that we can organise and tag them consistently, and filter/search to find what we want quickly. An email (.msg) file should not be treated any differently to any other type of file.