Yesterday an email was sent from my email address to all contacts in my address book. I didn't send this. It was sent one time only, and each email contained just a URL link, but different people reported receiving a different link.
I think it was sent from my local email client rather than web mail, because I don't have the complete address book in webmail.
I use Kaspersky Internet Security 2011. After this happened, I ran a virus scan: no viruses found. I also ran Trend Micro's online scan: again, no viruses found.
I also ran Panda's online scan, and it found a couple of inactive items. That path showed that these were located in my email data files (Thunderbird files) . These must have been executables that were sent to me through email that I didn't open, but deleted or that Kaspersky deleted automatically. I know that I didn't open these files; I am very careful about email and never open anything that I am not 100% sure what it is. Below is the entry in the Panda report (including the path) for one of these. Could this be what caused the email?
03682905 Generic Malware Virus/Trojan Active: No Severity: 0 Disinfectable: Yes No c:\documents and settings\user1\application data\thunderbird\profiles\ubkr56y7.default\mail\local folders\inbox[tube.zip][videotube.com.avi.exe]