Just was pointed to the following issue by an user:
if you save an EML File you sent (lets say 1 month ago) and reimport it, it is put into the drafts folder (which is expected behavior).
The send date is altered (even if you pull it to the inbox). To be exact: The senddate is altered to the actual date. E.g. If I sent it on 1st of november export it and import it today, it will be send on 11th of december.
This shouldn’t be that way, because sometimes an email is a important evidence.