I have choose sendgrid to sent email to my mail accounts. I used the php curl to do so.
When i run the curl scrip sending the mail to sendgrid server
$url = 'https://api.sendgrid.com/';
I got {"message":"success"} json response
But the message is not being delivered to my mail account (say google)
Your email was sent and delivered, but Gmail has marqued it as spam. There are a lot of ressources online and here to avoid to be classified as spam but it's a little bit too broad to be detailled here. For your Yahoo test, as explained here,
"deferred mail" is simply mail that was unable to deliver to the sender and has been added to the mail queue.