Also, all the financial institutions, credit card companies, lenders, etc. will address you with your name, - not customer, client, sir, or ma'am. And even if everything looks on the up and up, a spelling mistake or misuse of a word can tip you off as to the legitimacy of the email. Such as using the wrong spelling or wrong meaning to: your instead of you're, too - to - two, lose - loose, me - myself, threw - through, one - won, wait - weight, rain - reign, they're - their - there.
I could go on and on.