I love the way that AB removes capital letters from the titles of posts. It appears that you're seeking to protect a police constable ;-)
To answer your question:
Yes, there is a risk from simply opening emails but it's not as great as that from opening attachments. If you view your emails in an email client (such as Outlook Express) you should always disable the preview pane, as that effectively opens an email before you've actively done so.
However I find little difficulty in spotting potentially dangerous emails simply from their titles (or from the name of the sender) and happily delete them unopened. (My email service also automatically quarantines any that looks dodgy and then sends me a message to tell me about it).
Simply opening an email can't
directly cause an major damage to your computer but it might, for example, put some malware onto it that could then trick you into clicking on a link to something really nasty. That's why you should have the free version of Malwarebytes Anti-Malware on your computer and run it every so often. (I suggest running it once per fortnight or immediately after opening any email that looks dodgy):
https://www.malwarebytes.org/antimalware/