approve后email里就有50K确认
We're pleased to share that you have been approved for the MileagePlus® Explorer Card.
You will be receiving your new Card within 5-7 business days, along with details about your Cardmember benefits. When it arrives, please verify receipt by calling the number on the front of your Card.
Remember, you will receive 50,000 bonus miles after the first use of your Card.¹ That could be enough for roundtrip award travel.