收到了邮件，收 AMEX Delta Platinum 将发放 $50 的 Appreciation Credit。时间点是刚收了年费，我也付了年费，过几天就收到这封邮件了。根据 term，需要 45 天内不能关卡或者降级，不然会收回。。但是其实 45 天后降级还是能退部分年费，不知道 AMEX 怎么看待这种。
如果你有 AMEX Platinum 之类的，应该也是类似的发放模式
Terms and Conditions
$50 Statement Credit- Delta Platinum
You will be eligible to receive a one-time $50 statement credit after Card renewal. The statement credit will be applied to the eligible card account within 8-12 weeks of the account renewal month. This statement credit is limited to Basic (not Additional) Card Members only. Offer is non-transferable. If the eligible Delta SkyMiles Platinum American Express Card is cancelled, or you have downgraded or upgraded your Card up to 45 days after the first day of your renewal month, you will not receive the one-time $50 statement credit. American Express reserves the right to modify or revoke offer at any time.