Hi Janes,
Thanks for your reply.
Based on your reply, here is a way you can have a try to achieve the goal.:
1.Ask the related people to save the email to relevant folder in share point site.
2.Go to every folder, select Library toolsà Library, click the Connect to Outlook in the Connect & Export section.
3.The library will appear in the Outlook as a folder and you can access the content in it. Every time someone upload an email file to the library, you will can access the email in the outlook too.
If there are any questions, please feel free to post back.
Thanks,
Eben Liu