Which label text is good for "Enter email address"?

I'm about to place one text field in the log in area where user can enter email address and password for logging in, but I'm confused which text should I use for label and placeholder text?

Here are some examples where I found some different ideas.

Gmail:

  • Only placeholder with text "Email"

Yahoo Mail:

  • Only placeholder with text "Yahoo ID"

Outlook.com:

  • Only placeholder with text "someone@example.com"

Which one should I use? Only placeholder, or with label?

Also, a couple more question. If I use label, should the text and placeholder be "Email", "Email address" or "Enter Your Email", "Enter Your email address"?

Which one is better? "E-mail" or "Email"? Logically E-mail is the right one but somewhere I've also seen "Email" in place of "E-mail".