Mail merge from word display wrong characters

I have a word document that I am merging to send with Outlook. The source for the mergefields is an Excel Workbook.

The document and source is stored on OneDrive for Business.

When I merge to email I choose the document as an attachment. In the subject field I ad a text that holds special characters for Norway - ÆØÅ. The problem is that these are not displayed correctly when the email is sent from my Outlook.

If I move both source and document to the local computer, this does not occur.

I have been looking at regional settings in Office 365, Onedrive and the local computer. These are all correct (set to Norwegian).

I run Office 2016 on windows 7.

I am curious to know what the problem is. Are there settings that need to be tweaked in powershell, that are not visible in O365 admin?