Original sentence: Forwarding chain email may increase a user's risk of getting viruses, and may also increase the amount of spam received, since participant's email addresses are sometimes visible and may end up in the hands of spammers, either directly or via mailing lists archives on the web
Edited sentence: Forwarding chain email increases a user's risk of getting viruses, and can increase the amount of spam received, since participant's email addresses are sometimes visible and may end up in the hands of spammers, either directly or via mailing lists archives on the web