Every 2/3 days receiving Ransom demands from this bitcoin account

Received an email sent from my email address to tell me that he had hacked into my system. Quoted a password that he had captured (a password that I have never used.) Said that he had accessed my web cam (which I do not have) and will send captured images of me combined with images from said websites to all of my family and friends. Asked me to deposit 900.00 bitcoins to the above wallet. Stated that malware software had been installed .... Allowed me 48 hours to transfer money