I am sending calendar meeting invitation to user's email.
When receiver accepts invitation then it appears in receivers calendar but I am not able to get response.
Is there any way that I can get response and use it in my website?
Google Service Account is the perfect solution in this case. In this, users do not need any API detail instead site owner needs API detail. Read Google service account documentation and you will find solution of your problem.
来源：https://stackoverflow.com/questions/29514363/how-to-get-response-of-meeting-invitation-email-in-php