Database
[{_id:"something",email:"abc@gmail.com",contacts:[{_id:"123",status:"PENDING"},{_id:"456",status:"PENDING"},{_id:"789",status:"PENDING"}]}]
Query
db.collection.update({email:"abc@gmail.com","contacts._id":"123"},{"$set":{"contacts.$.status":"SUCCESSFUL"}},{"multi":false,"upsert":false})