Filters the content of the notification email for new user sign-up. Content should be formatted for transmission via wp_mail().
Parameters
- (3.0.0)
- ( MU ) . . .
- $content
- ( string ) Content of the notification email. . . .
- $user_login
- ( string ) User login name. . . .
- $user_email
- ( string ) User email address. . . .
- $key
- ( string ) Activation key created in wpmu_signup_user(). . . .
- ( array ) $meta Signup meta data. Default empty array. . . .
