Email attachments

A few years ago I opened an attachment from someone I trusted, and afterwards my computer went berserk.  I no longer open any attachments from anyone.  I've received some very important attachments from my son with pictures of my grandson graduating from the Marine Corps boot camp last week.  They're listed as JPG and txt.  Can I safely open these?  I believe Norton scans incoming email but is it totally 100% safe to open them.  I absolutely don't want to have to go through another bad experience with my computer like I did with that one attachment I previously mentioned. 

I'm just seeking reassurance that the Norton program does screen incoming emails adequately to prevent anything malicious getting through in the emails.

Thank you anyone, for any helpful feedback regarding this.

Buoybells