I tried to provide access to others, but now, nothing is reflecting under workflow. I think it is because I don't have access to that list & its items. If that is the case, then how can I use the "Mail To" functionality
My recommendation would be to set up a dummy user account with a separate email address that you can use for testing notifications, access, etc. There are numerous free services you can use to set one up, or you can access your IT department to create an email alias for you.