Here are some simple ways to save emails.
1. Don’t delete it.
2. Drag it to a different folder in Mail.
3. Print it, but instead of actually printing it, select the option to save as a PDF, and save the PDF in a folder on your computer.
4. Copy the content and paste into a text file using Pages, TextEdit, Notes, Stickies, or any app that accepts pasting content, such as ...
5. Create a calendar event and paste the content into the notes section.
Your imagination can probably find a dozen ways.
John Carter Sr.