SendGrid API V3 returns 400 Bad Request

I am trying to achieve send of mail via SendGrid API. Following is the JSON I am sending as a body of the POST Method ``` { "content" : [ { "type" : "text\/plain", "value" : "Hello, World!" } ], "personalizations" : [ { "to" : [ { "email" : "sahpranav1712@gmail.com" } ], "subject" : "Hello, World!" } ], "from" : { "email" : "iospranav1712@gmail.com" } } ``` and following is the return that I am getting ``` {"message":"Bad Request","field":null,"help":null} ``` This piece of info doesn't help much. The authorization is in place, and I believe correctly. Perhaps, I might have missed some sort of settings in the SendGrid App If it helps im using Objective-C. Please help!!