"分手信"英文里我们称之为：Dear John letter，

it's a letter written to a husband or boyfriend by his spouse or significant other to inform him their relationship is over, usually bcz the author has found another lover.

例如：She sent me a Dear John letter over the Internet.

其实Dear John letter已经变成“分手信”的统称，女人也是可以用它来表示男人给她们写的分手信，只不过常用于女人写给男人而已，它源于当年战时。当然，女人也可以用"Dear Jane" letter来表示男人写给她们的分手信，

例如：Should I leave him alone after a "Dear Jane" letter?