I setup an Exchange server and showed the client how to use web mail to access her mailbox remotely.
Me: Just follow these simple login instructions, and you can access your email from anywhere.
Next day, the client called me.
Client: When I got home, I did what you said but it didn’t work.
Me: Was your Internet working? Did Google work?
Client: Internet? I don’t have Internet at home! You never said I needed to have Internet at home – you said it would work from anywhere!