Scam messages work not through technical genius but by making you hurry. "Your account will be closed", "your parcel is being sent back", "last 2 hours" — they all have the same purpose: getting you to click before you have a chance to think.
The good news is this: the patterns never change. If even one of the signs below is there, that is reason enough to delete the message. When you can't be sure, the golden rule is: go not to the link in the message but to the institution's own app or official website. If there is a real problem, it shows up there too.