No envelope setting under "insert."

I just installed LibreOffice along with a new version of Xubuntu. For some reason there is no “envelope” setting under the “insert” button. Why is that? This is very disconcerting…Thank you in advance.

Add that menu entry manually:

  1. Tools → Customize → Menus tab
  2. set the Menu field to Insert
  3. click Add button, under Insert category find Envelope, click Add

Unfortunately, there is no Envelope listed under the Insert category in step 3. Now what do I do?