xxbenes,
I use Thunderbird free version 0.6. I have used it now for about 6 months and haven't had any problems with it. I changed it to my default e-mail client and quit using Outlook Express. Outlook Express is subject to more security problems than Thunderbird. Thunderbird will not allow a virus to execute if that virus is downloaded into the T.B. program. T.B. automatically disables any java script that could possibly allow the downloaded virus to be activated.
When you get out of T.B. I believe the java script then works for you. Anyway, T.B. is a great program. Have a nice day.