What are you hoping it will learn?

It ignores the sender ("From:"), since these entires are often spoofed by spammers. So if messages from friends are going into Junk, marking these messages as Not Junk does not whitelist their senders.

In theory, anyone who is listed in your Address Book should automatically be exempt from being classified as Junk, but in my experience it doesn't work 100%.

I take it these senders are in your Address Book? If not, please add them. You can easily create an additional address book inside the Address Book just for "friendly" senders that you might not necessarily write back to (e.g. certain "no-reply" style addresses.) You don't need to crowd your working address books with these addresses.

The junk classification works by identifying tokens that appear in messages, and looks for a significant correlation between the appearance of those tokens and your manual junk/non-junk classification, as you train it. If the spammers are clever and lace their stuff with lots of innocuous text then it's hard to differentiate between junk and non-junk messages. :-(

Hi Zenos, Thanks for your reply.

I would expect that if I keep marking an email as not junk it would at least remember that?

Also the emails it is marking are nearly all from people in my address book. Is there anything else I should try? Thanks

Is your mail provider Yahoo?

Hi and thanks for those replies. Yes the senders being marked as junk are in my address book, so I guess the whitelisting system does not work. I do BT email which used to yahoo, but I don't see why that should matter particularly for whitelisted senders. So is this a set up problem or is there a bug in the junk controls? Thanks.

Your e-mail provider may be marking these e-mails as junk, not Thunderbird. So you need to figure out the junk/spam settings for you e-mail provider.

Hi Bruce, Thanks for your reply but I don't think this is the issue. The email provider puts the emails it thinks are junk in a spam folder on the email server. The emails Thunderbird marks as junk are completely different and from people in my whitelisted address book so I can't see how it has anything to do with the email provider? Thanks Julian

The next thing I would try is to reset the training data for Thunderbird junk mail.

Menu: File: Tools: Options: Security: Junk. Click the button "Reset Training Data".