It is definitely legitimate and sends to the official Bitmain shop. You most likely did not receive because it was primarily pertaining to Z15 units. From the email, it is unclear if they want you to place a new order just so APW7 is removed or if they are allowing you to order additional units due to delay. Either way, I haven't received any response back from them on clarification. This was the actual email:
We sincerely apologize for the delay of Z15 July Batch you purchased, and appreciate for your kindly patience.
The Z15 will be ready to deliver recently, and we will send you compensation coupons after that.
I feel sorry to inform you, the Z15 miner will be only delivered without APW7 due to the production issue. Consequently, we will deduct the APW7 price with new order, and this amount difference will be transfered to you Bitmain balance account which can be used in future orders. You can match other brand 1800W PSU with Z15.
Pls kindly log into your bitmain account, use following link to make the order, choose usd wire as payment method, then finish the order.
https://shop.bitmain.com/en/product/detail?pid=redacted
Best regards
--
计宇铖 Yucheng
海外销售部 Sales and Business Development Department
Mobile: +86-173-0115-3002
北京比特大陆科技有限公司Bitmain Technologies Inc
北京市海淀区黑泉路宝盛南路1号院奥北科技园25号楼,100192
Building 25, AoBei Technology Garden, Baosheng South Road, Haidian District, Beijing 100192