Mozilla Thunderbird/Norton Antivirus question

[pagerbear]

OK, I've installed Thunderbird and successfully imported all my mail folders, settings and address books from Outlook Express (this was a godsend, because I had done something wrong when trying to manually recreate my Outlook Express settings). I changed my Mailwasher setting to Thunderbird instead of Outlook Express.

My question is this: with Outlook Express, every time I sent a message Norton popped up a reassuring little window telling me it was scanning the outgoing message. I don't get that with Thunderbird. If there is a setting to change on Norton or, I don't know where it is. Can anyone help me out, or am I worrying over nothing?