You can do it, but not with 100% certainty you will always get a notification.
There are two SMTP standards DSN and MDN, but they are both in effect optional, you have no guarantee that the email system your targeted email recipient uses implements them.
The easiest thing to try is to put in a "Return-Receipt-To:" (RRT) email header. Put some address as the content of the header. When a user opens an email message containing this header, the client's email reader will probably prompt the user whether or not to send a return receipt, if he complies, an email will be sent to the address you specify.
That's pretty easy to to in rails, you could do something like:
mymailer < ActionMailer::Base
headers['Return-Receipt-To:'] = 'email@example.com'
mail(:to => 'firstname.lastname@example.org')
If you want to you can set up rails to read these emails as well, or you can just use an email address you monitor and read them manually.
Again, THERE is NO GUARANTEE you will always get an acknowledgment !!!
Joe got a job, on the day shift, at the Utility Muffin Research Kitchen, arrogantly twisting the sterile canvas snout of a fully charged icing anointment utensil.