attach multiple .pdf documents to an email

What's the easiest way to

1. start an email in Outlook, then

2. display a document in Acrobat, then attach it to the email that's already started in Outlook, then

3. display another document in Acrobat and optionally attach it to the email started in step 1.

4. repeat opening documents and attaching some of them to the email started in step 1.

I have users with Windows 7 and Windows 10, and Acrobat versions X and newer.