This is to bring to your notice, there are many fake agencies or fraudulent people sending mails to individuals informing them about job opportunities in reputed and well-known companies. These people promote themselves as company HR's or having very good contact in the company and by providing fake identity cards.
In case of you or any of your known contacts gets such mail, you are advised to bring it to immediate notice of the management of the particular company which has been named as the employer.
You may verify the trueness of a job offer received via the internet by send mail to email@example.com to educate yourself about the probability of the claims being made in the mail/job listing being false / fraudulent.
Remember: Under no circumstance should you pay any employer / agency in exchange for providing any employment!