How to find if a plea for help is genuine??

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I know a girl from a poor family who is halfway through her studies but can't continue because of her financial state. I want to circulate a mail among my friends regarding this. But I remember myself ignoring such mails as scam. SO how do you prove that your plea is a genuine one and how to identify the scam. I really want to help her. I didn't pay her myself but took a draft for her college and paid. but I can't support the whole studies. What should I do??