I made all Lazy Approval configurations on my server. (Setup SMTP service, Central Administration settings etc.)
After that I tried to test Lazy approval. I created a simple workflow. I assigned flexi task and enabled Lazy Approval options.
When I got a mail from the system, I can see Lazy Approval footer text. But When I reply this mail with Lazy approvals' phrases nothing happened.
Thank you for all suggestions...
Note : I am using SharePoint 2013, Nintex WorkFlow 2013