First share your main mail file. Note: This will not allow your inbox to be read but this step needs to be done so all subfolders you select to share can be seen by the person you give permissions to.

Right click on your email address is the left side frame and select Folder Permissions.

Click Add and Look up the person's name you wish to share the folder with. Highlight their name and click OK.

Now select the folder you wish to share. Right click on the folder and select Properties, then select Permissions.

Look up and add the person you wish to share the folder with. Select and then OK like you did above.

If you wish for the person to be able to only VIEW the emails in the folder.

Full Details should be selected under Read. Leave all boxes under Write empty.

None should be selected under Delete Items.

Under Other make sure Folder visible is selected.

Select Apply and OK. Close your Outlook client then reopen it. See image below.

PART  2

This section is for the person who is opening the shared folder.

From the Outlook client select File Account Settings then click on Account Settings.

Highlight your account name and select Change. Click More Settings. Then select Advanced. Click Add and look up the person you wish to add permissions.

Click OK To add them . Then click Apply and OK.

Select Next and you are done. The folder has now been shared.

The folder that has been shared with you will now appear in the left side frame. Toward the bottom of your current listed folders. See example below.