Constantine Maroulis Arrested for Emailing Baby Mama

Constantine Maroulis has been arrested a second time in less than a week ... and both times his own baby mama is the one who put him behind bars.

The former "American Idol" star -- who was busted Wednesday after a physical fight with Angel Reed -- sent an email to her Sunday, which violates a restraining order prohibiting any contact with her.

Constantine's rep tells TMZ, the email outlined various things that Angel had supposedly done that led to Wednesday's fight -- a fight in which he says he merely defended himself. The rep says the email was supposed to go to Constantine's lawyers, but he accidentally cc'd her.

He was arrested Sunday night after Angel complained about the email. He's already bailed out.