It looks like something got into my yahoo email I noticed a few days ago there was quite a few MAILERDEMON notices in my inbox for items that could not be sent. I checked my sent folder and there was a lot of outgoing messages with no subject. I have seen those in my inbox from people I know but I know to never open them or click the link. This has happened now for the last three days with emails going out. Is there anyway to stop it? I am on a mac and don't have any virus protection. Should I get some?