I'm a little unclear about the difference between junk and spam.

Thunderbird uses the term 'Junk'. Many providers use the term 'Spam'. Yahoo are using yet another term - 'Bulk'. At the end of the day it all means the same thing.

Thunderbird learns to recognize junk by what is in the Junk folder?

It's the other way round. Messages which Thunderbird classified as Junk are being moved to the folder you designated as Thunderbirds Junk folder. Note, you can also designate a 'Spam' folder as Thunderbirds Junk folder in your account settings.

Training the Thunderbird built-in adaptive junk filter is an entirely different matter. http://kb.mozillazine.org/Junk_Mail_Controls

what exactly is the Spam folder for, and why do things end up there?

If you use IMAP the Spam folder may be provided by your email provider. There's a spam filter on the server too, and messages classified as Spam on the server end up there.

Why wouldn't I want spam to be considered as Junk, with regard to the adaptive junk mail controls?

You could. The flip side is you'd need to download all messages already classified as Spam on the server to your local disk. You can choose what fits best for you.

Thank you. But I guess the question is whether what lands in the Junk folder needs to stay there in order for the adaptive filtering to work. That is, I call an e-mail Junk, it lands in the Junk folder, and the adaptive junk filter is trained to look for those kinds of e-mails. But can I delete the Junk folder? That is, when I delete that folder, is the adaptive filtering erased? Or does the adaptive filtering DEPEND on what is currently in the Junk folder?

By the same token, I'm presuming that what lands in my Spam folder is not automatically marked as junk, and does not train my adaptive filter. That is, if I want my adaptive filter to reject an e-mail in my Spam folder, I have to manually designate those spam e-mails as junk.

Now, that's a really good point that Junk is, for my IMAP system, a local folder, and TB can pay attention to it. Spam is just sitting on my server, and unless I download it, TB won't be able to do anything about it.

In a nutshell, Junk is what I tell TB an e-mail is, and spam is what some other provider tells ME is junk (but doesn't tell TB it is junk).

OK, on examining the Junk_Mail_Controls page, I may have answered one of my questions. It says "You don't need to keep the messages you have marked - marking stores the information it needs as tokens in the training.dat file." So my Junk file is just telling me what TB has used in its adaptive training. It isn't using those mail files anymore. If I delete my Junk folder, the training will remain.

I gather that if I want to archive that training (in case I accidentally reset it), I can just save the training.dat file.

By the same token, I'm presuming that what lands in my Spam folder is not automatically marked as junk ...

Thunderbird automatic junk filtering happens when a message is received. Typically messages in the Spam folder have already been filtered there on the server. If you have synchronization turned on for the Spam folder, Thunderbird would download those messages and run them through the adaptive junk filter.

... is not automatically marked as junk,

Training the adaptive filter is a manual process by marking a message as 'Junk' or as 'Not Junk'.

if I want my adaptive filter to reject an e-mail in my Spam folder, ...

Not sure what you mean with 'reject'. I guess that means to 'classify a message as junk'.

... I have to manually designate those spam e-mails as junk.

That would only be the case if the Thunderbird junk filter doesn't classify the message as junk. As said before, the message will need to be downloaded by Thunderbird to run it through the junk filter. That only happens automatically if you turn on synchronization for the Spam folder. https://support.mozilla.org/kb/imap-synchronization

Junk is, for my IMAP system, a local folder

By definition, with IMAP there are no local folders. There may still be messages not classified as Junk on the server. Thunderbird may classify those as Junk upon downloading, and move them to the Junk folder. Note, you could also designate the Spam folder as Thunderbirds 'Junk' folder, and just delete the original Junk folder. I guess I said that already in the reply above.

Spam is just sitting on my server, and unless I download it, TB won't be able to do anything about it.

Correct.

I gather that if I want to archive that training (in case I accidentally reset it), I can just save the training.dat file.

It is recommended to backup the entire Thunderbird profile. Using IMAP does not make backups obsolete. https://support.mozilla.org/kb/profiles-where-thunderbird-stores-user-data#w_backing-up-a-profile

OK, we're getting close here. If I have a filter that takes e-mails that I don't like and sends them to my Junk folder, is that the equivalent of manually marking that e-mail as junk, for the purpose of training the adaptive filter, or do I have to manually press that Junk button to make the adaptive filter pay attention to it?

By default a filter runs prior the the junk filtering. So if a message is moved to the Junk folder by a filter, it bypasses automatic junk filtering, and you'd need to run junk mail controls manually on that message.

Once again, training the adaptive junk filter is a manual process and something entirely different than classifying a message as junk.

If you want all your junk/spam emails to go to one folder eg: the server Spam folder then in Account Settings window for that imap mail account choose the server Spam folder as the destination.

• Right click on imap mail account in Folder Pane and select 'Settings
• Select 'Junk Settings'
• select 'Enable adaptive junk mail controls for this account
• Select any of your address books to act as Whitelists.
• select 'Trust junk mail headers set by SpamAssassin'
• select 'Move new junk messages to'
• select 'Other' and choose 'Spam' folder on imap mail account'
• click on 'OK'

Excellent. Thank you.

Of course, once an e-mail has been sent, by a filter, to the Junk folder, I don't have the option of manually declaring that e-mail to be junk, for the adaptive filter. I guess I have to declare it as NOT junk, so I can manually declare it to be junk?

once an e-mail has been sent, by a filter, to the Junk folder, I don't have the option of manually declaring that e-mail to be junk

You can manually mark a message as Junk at any time, and by doing so train the adaptive filter. But I guess there's not much point in doing that if the message hasn't been downloaded yet.

I guess I have to declare it as NOT junk, so I can manually declare it to be junk?

No, that would be silly. Once a message has been classified as Junk by Thunderbird, either manually or automatically, you'll see the little flame icon for that message in the thread pane.

But you said

"Training the adaptive filter is a manual process by marking a message as 'Junk' or as 'Not Junk'."

So if a message is in the Junk folder because of a filter, it wasn't a manual process that put it there. So how does that message get used to train the adaptive filter once a filter put it in the Junk folder?

So if a message is in the Junk folder because of a filter, it wasn't a manual process that put it there.

Correct.

So how does that message get used to train the adaptive filter once a filter put it in the Junk folder?

You'd need to manually mark it as junk.

In any case, I think it's hopeless to try fighting spam with static filters.

OK, but as I said, if the e-mail is already in the Junk folder, you can't manually "mark it" as junk. You need to pull it out of the Junk folder to do that. Isn't that correct?

But that's a good point that static filters are of limited value in fighting spam.

Isn't that correct?

I don't think so. You can manually mark a message as Junk at any time by right-click the message - Mark - As Junk.

As aid before, I guess there's not much point in doing that if the message hasn't been downloaded yet.

Ahhhh, right click Mark>As Junk. Yes! You don't get a button to do it, but you can do it.

Seems a bit weird, having to manually mark e-mails in the Junk folder as Junk. But it can be done.

I should add that, if I understand it correctly, "junk" can mean two things. (1) That the e-mail is sitting in the Junk folder, perhaps put there by a filter, and (2) that you have manually designated the e-mail as junk. In principle, (2) is formally junk, and (1) is just where you've decided to put stuff that you have not yet declared to be junk in a folder that happens to be called Junk.

If you have a Thunderbird message filter moving emails to junk then you can also mark it as junk in the filter.

eg: Apply filter when 'Getting new mail' 'filter before Junk classification' Set the filter parameters Perform these actions: 'Set junk status to' and select 'Junk'

then when Junk classification runs it should pick up the 'Junk' status and auto move to 'Junk' or 'Spam' depending upon which folder you have selected junk to be put in.

Thank you. That's good info. The point is that in your filter, you can not only send something to the Junk folder, but actually set its status to junk when doing so. The latter, I presume, is equivalent to manually setting that junk status, for the purpose of the adaptive filter.

I'm still scratching my head about the fact that things in the Junk folder do not necessarily have the status of junk. I mean, why would I put something in that folder if I didn't want it to have that status?

If the server sets as 'Spam' it goes to Junk. Junk settings can select emails detected by eg: SpamAssassin as Junk. If you have a filter that sorts the email and auto puts it in Junk. If you manually choose to mark as junk for email that has got into Inbox, as junk. Basically, if a filter does not capture a specific email and put it in Junk, then you can help train the adaptive filter to auto put it in Junk.

All of these emails end up in the Junk folder which is the desired effect.

At the moment you seem to be wondering how you can get the adaptibe filter to understand what is and what is not junk when you have created or used other filters to detect junk.

Do you intend to remove all your various filters that currently put emails in Junk and therefore rely on the Thunderbird adaptive filter ?

Well, what I had been doing was just putting all e-mails that my filters were set to pick out as junk in the Junk folder. I *thought* that by just putting them in the Junk folder, it would officially designate them as junk, for my adaptive filter. But evidently it does not.

I have now changed my filters to not only put those e-mails in the Junk folder, but ALSO to specify them as junk. Of course, when I mark an e-mail manually as junk, it is officially junk-ified, and I have it set to put it in the Junk folder when I do.

I'll say again that it is quite bizarre that what lands in the Junk folder is not automatically formally marked as junk. Why would you ever want to put something in that Junk folder that you didn't want to be officially (for the purposes of the adaptive filter) considered junk?

When I put something in my wastepaper basket, it is officially because I want to dispose of it. My wastepaper basket isn't a receptacle that stores paper that I have to decide whether I want to get rid of. That is, in the Mozilla scheme of things, what is in the Junk folder isn't necessarily junk. Might be, but might not be.

re :what is in the Junk folder isn't necessarily junk. Might be, but might not be.

Correct. It is possible that an email could get marked as spam by a server filter and it is not spam. Hence why most emails in junk really are junk but not 100% of the time. Which is why there is a facility to mark as 'not junk' to move back to Inbox.

Trash Most people say it is trash, delete and put in Trash. But you can guarantee that someone will delete in error hence the need to be able to recover it.