Totally Disable Junk Mail in Thunderbird

I have a problem with junk mail filtering in Thunderbird and I just want to turn it off completely; however as far as I can see it's not actually enabled anywhere; and further to that I went into my server and added to the whitelist one email address in particular (which is constantly being marked as junk in Thunderbird). I did this just to rule out the mail server as a possible culprit, but I didn't think it was anyway because a) I think it is currently set to delete junk, and b) I think that when mail servers don't just delete the junk they mark it with SPAM or something in the subject.

So the things that I have done to turn off junk mail are the following:

1. Account settings > Junk settings > unticked "turn off adaptive junk mail … " ( this I would have thought would have done the trick alone but not so) … I also did this under local folders just in case that was what was doing it.
2. Checked "Do not mark as junk mail if the sender is in .." ticked all …. and the sender is in all too. I know this shouldn't matter in light of 1 but I did it anyway.
3. Checked for a message filter under tools>>message filters. Only my own ones are there.
4. Tools>options>>advanced>>junk unticked everything (and also clicked "reset training data" in case that was it)

I can't think of anything else but I have read some posts on the internet where others are having a similar problem. I have been a happy user of Thunderbird for about 5 years now but unfortunately if I can't fix this I'll have to switch to something else, who knows what, as it's actually unreliable as it is.