According to the BTC Markets, the company uses an external email system to send out updates to its customers. In the process of sending out correspondence, the company’s customers’ names and emails were included in the ‘to’ section of emails, rather than being blind carbon copied or individually addressed.
Imo this is a somewhat very silly mistake, that could later, sometime 'down the road' cost someone their funds, I think this exchange should know better to avoid such mistakes, that's the thing with centralized establishments in crypto, you can't entirely trust them, that's why you should always remember to be your own bank and store your funds either in a hw wallet or in a wallet that you alone have the private keys, and never on an exchange.
Having said that, if you use that exchange, avoid clicking random links even if they look legit and verify any information or message you receive going forward, and mind you that despite the fact that this data is already in the black market, the phishing attempts may not start immediately, it could be after many months, so don't only stay vigilant for a while, but always be.