Password Reset Emails Not Being Sent

Summary

Users click on the Password Reset link on the login page but never receive an email to reset their password.

Content

Users click on the Password Reset link on the login page but never receive an email to reset their password.  

Even if I go into the Security console and click on a users account to reset the password, I must reset the PW manually as the email never is received by the user.  

Any ideas if this is a configuration issue?