Obviously - do not open it...
If this is potential business and you want to confirm prior to deletion...
Send an email back to the provider - preferably from a non-business email account...
If you respond to the email from this email - you are confirming the email address as an "active address".
If you get a response with a phone , do the obvious - call and speak -
Normally you will not receive a response as this is done "en mass" and not a single targeted box.
You can also perform a "reverse look-up" on the email address -
Check the address in the header - is it valid?
Google for instructions... Use a site like http://www.dnsreport.com
All this can be done - with suspicious email....
----- OR -----
BEST ANSWER - DELETE IT
Unfortunately, many suspicious emails today, when opened, have the capability to go through your computer's hard drive and steal information or destroy the system you are working to protect.
Better to be safe than sorry. When in doubt - delete.