I want to create a web application using PHP which will allow to connect Facebook accounts with my application and once they authenticated my application can fetch inbox messages of that user and can auto reply to the messages received against authenticated Facebook accounts.
Also, allow user to send messages manually from my application to Facebook inbox.
Is this possible with Graph API or any other Facebook API which will allow me to do above mentioned things.
Some people was told that this feature is no longer available after Facebook Graph API v2.4.
2
Answers
Neither of those two things is possible.
You can not read the messages of user accounts any more, and you can not reply in their name either.
The only messaging that can be handled via API, is that between a user and a page.
Assuming you refer to Page conversations, not user conversation, see /conversations and /messages docs here:
https://developers.facebook.com/docs/graph-api/reference/page/conversations/
https://developers.facebook.com/docs/graph-api/reference/v5.0/conversation/messages