If the bot sees case 2) it means you have an account, so to continue, the hackers will try to brute force the password. It's a way to clean their email lists.
Copy the link by right-clicking and selecting "Copy URL" or by checking the email source code (but don't open it). If it leads to the real HitBTC website, then it is most likely something trying to login/register with your email.
If it leads to a fake website (e.g: hltbtc.com), then you have your answer.
In any case, since you don't have an account there, I wouldn't worry about this.
Note: I have already received the most valuable answer that I wanted to know. So no need to increase this discussion anymore. I am locking this thread to reduce spam. Thanks, all who already tried to solve my issue.