Issue Summary

When using Edge Office Viewer xlsm attachments are opened in Word although xls and xlsx files are opened in Excel.

XLSM attachments have the following content-type parameter value in the media server.

content-type: application/vnd.openxmlformats-officedocument.wordprocessingml.document

XLS and XLSX files have the following:

content type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet

Steps to Reproduce

1. Create a page.
2. Attach an XLSM file to the page.
3. Open the page in Edge browser.
4. Click (...) More actions > Attachments > Attachment name

Expected Results

The file is opened in Excel viewer.

Actual Results

The file is opened in Word viewer:

Workaround

Downloading the xlsm attachment and opening it in excel.