Very similar to any ordinary text message, except these are always imflammatory, hateful, insulting, belittling, and generally negative in content, and always from the girl or guy you just recently dumped in a very painful, and likely humiliating, manner.
Me: Oy. You know how I broke up with Lynn on Sunday night? I woke up this morning and checked my phone, and had 33 different mails from her. She, uh, has quite the potty-mouth.
Jeff!: Nothing but Ext Messages, huh? Surprised?
Me: I guess not. I did accuse her of sleeping with my brother. Then I called her that something that rhymes with "manipulating bitch".
Jeff!: Expected backlash, Mr. Jerk-Face. You don't even have a brother.