What is the ruling on addressing a female using the masculine form?

Women address each other using masculine forms, as if they were men; this is an imitation (tashabbuh) that is forbidden, according to the Prophet's (PBUH) saying: "Allah's Messenger (PBUH) cursed men who imitate women and women who imitate men." It is also among the false, vain speech forbidden by Allah's (the Most High) saying: "And shun false speech."