So you receive an email with an invoice from a company / business that looks incredibly good.
You then go to click on a link in the email to pay your invoice.
The first thing you should do is stop and look at the address where the email is coming from.
You will see from the image below that this Telstra invoice looks tremendous but is obviously fake when you look at the address that it was sent from that follows the image.
So look at the address and think before you click.