I wanted to make a correction in the post above. Is it no longer possible to edit the first post in a thread? The drop-down menu doesn't give Edit as an option.

Just want to make it clear. Thunderbird is based on Netscape Communicator and has nothing regarding Eudora in it's roots.

For a very brief time about 15 years ago the Qualcomm paid some developers to build a Thunderbird addon called Penelope that worked with exactly one Thunderbird release that they marketed as Eudora OSE. It lapsed into history with the next Thunderbird release as the addon was a binary one and needed to be rebuilt for each Thunderbird release. Qualcomm only ever built the addon for a single release. So the Thunderbird Eudora links are very tenuous indeed.

Now I have no idea what Eudora did with SPAM, I used it for a couple of weeks in he early to mid 1990s and hated it. However from the posts over the years I get the feeling it offered some sort of block list for email addresses. Thankfully Thunderbird ignores the sender when determining is an email is "spammy". User insistence on marking mail as spam based on the from has other poor outcomes going forward

Now as I read your issue, your junk mail is not going to the junk folder. As I have never used that feature (I simply refuse to use anything but the learning filter Thunderbird comes built in with) I really can not comment specifically in relation to filter use.

What I do know is for mail to successfully be moved the storage file must be available for writes to update it. Unfortunately most folk with the time to do spam filtering manually also have antivirus products scanning in the Thunderbird profile folder immediately after a file changes (add a new mail to the folder) unfortunately your filter is also attempting to modify the file. The file contention between a period of internal intense opening and closing of file and the scanner plodding among with it's 10 minutes per GB scanning sees the change simply fail silently in the background.

So the first things that must be ensured for reasonable Thunderbird experience are. 1. The profile folder is not being scanned on each file change. Prefereably it is excluded from everytinhg except periodic full system scans. 2. The profile location is not on a place where it is synced to the cloud, or subject to streaming backups. Essentially issues arise if it is moved from the hidden appdata folders it defaults to as third party backup and scanning software treads data in those hidden folder locations differently to say "my documents". Even storage on network locations like a NAS can cause issues. 3. Wherever possible filters are run after junk classification. While this is more important for IMAP accounts, it does allow for the filtering to be slightly delayed which also helps with contention issues. Filtering after junk classification is especially important where you are marking mail as junk as the inbuilt junk filter should be allowed to go first. All the thousands of junk mail in filters will affect how it reacts to new email. It is also important to never use a filter to mark a message as junk based on the sender. That will simply corrupt the learning algorithm as it only has regard to the message, not the sender. Marking mail as junk based on sender can actually make the in built filtering worse and increase the numbers of false positives.

Based on what you've written, I am taking away three things:

1. You have an almost neurotic allegiance to Thunderbird, so much so that you feel compelled to give a long lecture to anyone who criticizes it;

2. Thunderbird does not have a well-designed filter feature; and

3. Despite the fact that the program is updated every ten seconds, there is no solution to my problem.

Does anyone else have a suggestion?

I had a lot of tries writing a response to that, but unfortunately I feel anything I write will be an utter waste of my time, so I will simply close the topic.

Your interest in facts, correct information and common causes and therefore fixes is lacking. You will most likely not get a fix because the problem is probably not in your mail client.

Your response to me was not helpful -- and I certainly didn't get the impression that you were trying to BE helpful. I have a fairly new computer, and I installed Thunderbird just last year (actually, possibly two years ago). If it didn't install correctly, that's not my fault. I didn't even understand everything that you said.

Do you have any specific recommendations as to how I can fix this problem? If you don't, then I want to hear from someone else.

I gave you a very long list of things that might fix the issue. You are hanging out looking for someone to tell you press this and it is fixed. Not going to happen.

I have had spam/junk not move. About 20 versions ago. I changed antivirus program and the issue "went away" It was not the prompt for the change, but a side effect.

Fundamentally filters work, I use them every day. You are saying the message does not move to junk. That is an issue not only with filtering and is most usually caused by external factors. But you wait it out. Some brave soul might come along one day, or you will be another of those complaining about lack of support because your predetermined cause or source of the problem is not the cause at all. There are lots of folk looking for support that are very unhappy with what they get, mostly crickets. The cause is not a lack of folk trying to help them.

Listen, I'm not a tech person -- although I did do a little programming when I was younger. I did enough of it to know that if a system or program is well designed, then it does what it is supposed to do. Really, the biggest thing I have gotten from you is that Thunderbird is poorly designed and temperamental.

Now you're complaining about my attitude, but my attitude isn't the only problem here. You started out your first response with a long scolding about how Thunderbird was developed from Netscape and not Eudora, and about how you don't like Eudora. Who cares? You could have corrected my wrong impression in one sentence.

Yes, I want answers. I'm not the behind-the-scenes computer person I used to be. I described the way I set up my filter thinking that I had probably done it wrong, but basically what you've told me is that even properly designed filters may not work in Thunderbird. So the design of Thunderbird is the problem, right? That seems to be the answer.

I am making one change on new filters, and that is that I am applying the filter AFTER junk filtering instead of before. However, BEFORE is the default for the feature, so I can't be blamed for doing that.

My experience is "Fundamentally, filters don't work." They didn't work on my old computer which I scrapped in late 2021, and they aren't working on my new computer -- and it didn't matter what antivirus program I was using. So that seems to be my answer -- Thunderbird's filters are temperamental and don't always work.

Eudora, by the way, was a fabulous program. It's junk filtering was amazing. Much better than what I am experiencing now. I used it for ten years after Qualcomm stopped developing it.

If anyone has specific advice, I'm listening.

I suggest you use some debugging strategies. My suggestion is to follow @Matt's suggestion to set the filter after Junk classification and to start with just confirming that you're selecting the message correctly. For example, I would just tag the messages. Once that works, then I would set to delete, ignoring the Junk process. Thunderbird's filtering is quite good and used by thousands of users. Also, as @Matt wrote, anti-virus products have frequently been involved where standard features are not working properly, so that may be a possibility, but I would explore that only if the selection process fails.

I'm late coming back because I was sleeping.

Let me start out by apologizing to Matt for being so cranky, which happens when you get old and sick. We got off on the wrong foot. You didn't like my criticism of Thunderbird, and I didn't like your criticism of Eudora, which I adored.

Thank you, David. I'm already experimenting with setting the filter after junk classification.

Can you expound on what you mean by "confirming that I select the message correctly"? I found the Tag command in the filter window. Looking at my first post, in which I outline all the steps I am taking in each filter, can you suggest where the Tag command should go, and also suggest any other changes that might help? You too, Matt, if you are still interested.

As for changing the location of the Profile folder, which Matt mentioned, I don't think that's something I want to deal with. I'm concerned that I might bollix up the whole program.

Thank you.

What I was trying to convey was that, in debugging a filter, it helps to first ensure that the selection is working and then to work on the action. Since the moving to junk was an issue, I felt that taking an easier path first would confirm at least part of the filter. For example, set the filter to handle Stimulus with a tag would confirm that at least part of the filter is working. Then, you can pursue disposition of the message. Since your original post was not able to confirm that anything was working, this would be a start. I would just set the action to assign a tag. You would then see it tagged in the inbox.

As an aside, my dear spouse still uses Eudora, which she has used since the 90s. And she gets grumpy whenever I suggest upgrading to Thunderbird. Funny.

So, David, here are the contents of the filter I am presently using:

- Manually Run - Getting New Mail: Filter after Junk Classification

- Match any of the following - Subject - Contains - Stimulus - From - Contains - Stimulus

- Tag (???) - Set Junk Status to - Junk - Mark As Read - Delete Message

Did I place the Tag command in the right place, and are there problems with any of the other commands? Is the "Set Junk Status to - Junk" command the right thing to use, or should I use another command that simply moves the email to the "Trash" folder. I guess I don't need the "Mark As Read" command. And since Thunderbird doesn't actually delete emails (it will only move them), perhaps I should remove "Delete Message".

Any thoughts on what I've said? Thanks!

Until the tag works, I would remove the other settings. The goal with tagging is just to confirm that you are selecting the messages.

Thanks, David, though I don't really understand. You are saying that temporarily I should just tag spam, just to see that the Tag command is working? Then what?

I apologize for confusing you. I suggested tagging just to confirm that your filter was selecting the desired messages. Once you have that working, you can then remove the tagging and focus on ultimate action. I suggest either deleting or moving to trash. Your first post indicated hat the filter was not working and, since filters have two components, I wanted to initially confirm that the selection component was functioning.

Thanks for clarifying, David. So far, having the spam filters do their job before the custom filters seems to be helping. I'm still working on it.

By the way, I'm curious about something. When I receive notifications from Mozilla that someone has posted a reply to my question, the notification email doesn't include the URL of the thread, so I have to go searching for it through all my open windows. Why is that?

About spam filtering...

I used to use Eudora. I used POPfile to filter spam. POPfile inserts headers into the mail saying whether it thinks that a message is spam or not. Eudora filtered on that header. When I started using Thunderbird, I kept POPfile in place and it worked. But I later switched to Thunderbird's native filtering, which now works well too.

All of these use Bayesian filters, though POPfile also has a lot of other clues it can look at with assigned weights, and its Bayesian filter was actually rather weak. A Bayesian filter's accuracy is based on its training. It starts out knowing absolutely nothing. As you mark messages as spam or not-spam, it learns. A few thousand messages later and it's working pretty well, and I don't use POPfile any more.

Thunderbird's Privacy and Security Options page has a few options: Set your default junk mail settings. Account-specific junk mail settings can be configured in Account Settings. [x] When I mark messages as junk:

Move them to the account’s “Junk” folder [ ] 
Delete them  [ ]

That helps too.

Thank you, Fred. I'm getting some useful advice now.

Just to let you know, setting custom filters to operate AFTER junk-filtering seems to have improved the situation. I never did that before because the default for filters was BEFORE, which I now see as a mistake.

One other thing: I started this thread complaining about spam with the word "Stimulus" in the Subject line which my custom filter was not seeing. Well, it turned out that the spammer was -- at least in some instances -- replacing the "L" with a capital "I". I have now added "stimuius" to the filter. I need to be on the lookout for such subterfuge.

Thanks again for the help. I hope people are having a good Thanksgiving.