Client Integration?

I'm using NIS 2010 17.7.0.12 with Windows 7 64 Home Premium.

Because I'm losing emails somewhere my ISP told me to turn off email protection in NIS so I have turned off Antispam. I should say I am using Mail Washer Pro anyway. 

 

The Help file in Norton tells me how to integrate my email client which is Thunderbird 3 but there is no setting that I can find as to how to do this. The Help doesn't seem to match anything in the Network Settings options.

 

I also want to know if I can check somewhere in NIS to see what emails (if any) have been rejected. Is that possible? In other words, I want to try and establish whether Norton is losing my mail or my ISP.

 

I would appreciate any help here please.

 

Thanks.