ok, seems the problem is solved: the virus I was hit by was a mytob variant. it seems like the signatures are not yet included in clamav. while searching in their database I found the mytob signatures were included in the daily.cvd while signatures for older viruses were included in main.cvd file ... I do not know what this means exactly
I did a freshclam but I already had the latest definition files, I thought about restarting clamav or clamd and there was no such process running, is that right? does the process get started when an email is scanned or is there something wrong with my install?