Contact Form 7 – Datalist

This control works in a similar way to the existing drop-down menu, but rather than a fixed list of options that the user must select from it is presented to the user as a textbox.
Once the user begins typing a list of possible options will be shown, selecting one will fill in the rest of the field with the selected option, if the desired option is not present in the list then the user can type in their own option.