Word 2013 not saving recipient address or attachments

Question

When creating an e-mail in Word 2013, then saving it (as a.doc/.docx document), both the recipient's address and (eventual) attachments are not saved inside the created file, and as such not available anymore when you reopen it.

In previous versions of Word, this was not the case.

Steps to reproduce:

1. In word 2013, create a new document
2. Using the "Send to mail recipient" button (which is not on the ribbon by default), show e-mail related fields (To, Cc, Subject, ...)
3. Write your e-mail, including a recipient and a subject, then attach a file.
4. Use "Save as..." (.doc or .docx, it doesn't matter) then close it.
5. Open it again: recipient address and attachment are gone.

The same steps in a previous Word version (I tried with Word 2003) work fine and all data is saved as expected.

If you open with Word 2013 a file created and saved in eg. Word 2003, recipient address and attachments are there. If you save it again from Word 2013, attachments are stripped, but recipient address is kept!

This stripping behavior makes think of some security option, but I was unable to locate any way to influence this behavior.

How to configure Word the keep the complete e-mail data when saving, as it used to do in earlier versions?