False Allegations Using Gmail Id

Hello Sir/Madam, my friend is working in a nationalised bank as a senior manager. She recently got married and comes to know the Sadistic behavior of her husband and both sides decided to opt for mutual divorce. Due to the grudge on her, her husband sent email stating false allegations using unparliamentary language and tried to defame her good reputation to the highest authority of the bank. He don't have any bank account of that bank and he is not a customer of that bank. He simply created one fake Gmail account and sent the email to the higher officials. After few days my friend comes to know that the email sent by her husband only. Now, she wants to file a case for the false allegations. If she files a case, did he gets any punishment and what sections she needs to put to file the case. Please let me know. Thanks.