Hello, I am a new Mac user (first Mac purchased June 2008, Macbook 4.1) and am hoping to get some advice from some experienced Mac/tech folks on how to deal with what I assume is a virus/spam issue. Yesterday, my internet-based email account (yahoo) sent out a spam message from my account. I did not construct, write or receive the email prior to it being sent out. It went out to everyone in my address book. The messages subject line read good mood good shopping and encouraged recipients to go to a website to buy electronics. Needless to say, people were not thrilled to get such spam from me. In addition to sending out this email, whatever caused it, wiped out my entire email address book in yahoo. I no longer have any of the email addresses of my contacts. I have had the account since 1998 (!) so you can imagine the frustration of losing all that information. Fortunately, I do have most of them in other spots, but as I travel and live abroad, it is very handy to have an internet-based account with all those addresses, accessible wherever I am. I should mention that the mailing occurred while I was away from the computer, but while I was remained logged into the yahoo account. No one could have had physical access to the computer itself, as it was in a locked apartment. But I wonder if somehow remaining logged in, and on-line left me vulnerable for this? I also have the Microsoft office suite on my computer, I need it for my work. I know these programs can be targets as well. I immediately changed the password on my yahoo account, deleted all the emails related to the message (I received a couple of copies as I had my own email address in my address book), and tried to contact those folks whose email addresses I could recall to warn them to delete. I also switched to a gmail account. I contacted yahoo, but unsurprisingly they could not offer much in the way of explanation or suggestions on how to prevent/rectify the situation. I also contacted Mac Support and ran tests on my harddrive to see if there was any damage. According to the tests we ran, my computer looks fine. While I am grateful for that, I am still concerned that I have not completely eliminated the problem. I have read the forum discussions debating the utility of installing an antivirus program on Macs, and understand that the general low to nonexistent level of risk of virus for Macs. However, given what has happened, I am not sure how to proceed. Part of why I switched to Mac was its generally low virus risk, and now I feel very vulnerable indeed. If it wasnt a virus, what exactly was it that did this? I dont open any dodgy websites and never open mail I dont recognize; after 12 year of PC use, I am pretty well trained to avoid junk, so I doubt that it came in that way. All this background is to ask the following questions and ask for any advice on how to deal with this situation. 1) Any idea on how this could have happened? Was it a virus/worm/trojan? Was it because I had my internet open? Is it possible to have a virus infect an email account, but not the computer itself? 2) What additional steps should I take to mitigate the damage and further prevent this type of thing from happening in the future? 3) If I invest in anti-virus protection software for my Mac, which one should I use/buy/download? Any recommendations/reviews/suggestions on where get more information ? Thanks for your help and time. I have found reading the forums very useful and hope someone has ideas for me. Regards, S.