I finally moved my old Outlook Express stuff to Thunderbird, and am downloading all emails stored on POP3 server.
But I don't want Thunderbird to download them all at once. I want 20 at a time, so I can see them and delete junk ones and move remaining to their proper folders before downloading more.
I can't find a button to stop downloading. Once I make Thunderbird download emails, it just keeps downloading and the only way I found to stop it is closing it.
Is there a better way?
NOTE: while the specific counts are not possible, you can switch back and forth between offline/not offline, but it's a pain, requires confirm click.
Otherwise: Download all emails. Use spam emails to train your thunderbird spam filters once all the emails have downloaded. Start at the beginning of the list. It's a one time operation, don't overthink it. As you assign 'junk' status to emails, you can rerun the spam filters on the inbox until it's properly trained, and most of the subsequent emails will get moved to the Junk folder automatically after you've created a decent set of spam samples. If you give the junk filter a few hundred samples it will be pretty accurate. Check junk folder for false positives, mark not junk, repeat until it's good. Much less work than doing it 20 emails at a time.
Thunderbird's builtin spam filters are quite good once properly trained.
When viewing (including preview mode) spam emails, make sure that third party image view is disabled, otherwise you will be validating your email address in the spammer email databases (they use often images or links with unique id's in them that when loaded or clicked simply validate your email address as current). Ideally disable all html viewing and view in text mode only, no html.
As with training your spam filters, the same applies to email rules/filters, which are even easier to create and run.
Create filters that move the emails to the desired folders after you make the folders, and after you create each filter, run the filters on the inbox again.
Because the user is fairly stubborn in this case, here's the basics when interacting with a new piece of software:
Check to see if the desired feature that another similar program has is supported. If it isn't, and you're sure you didn't just miss it, the developers don't care about that feature, or the feature is not technically possible due to how the software is constructed. The users in general also don't care about that feature, otherwise someone would have filed an issue, and others would have piled on over time, until the devs got tired of that issue and made it happen. In this case, we can assume none of that happened.
Check to see if the program supports extensions of some kind. Thunderbird does, so look for an extension that extends the features of the software to do what you want. If nobody wrote this extension, this means that no person capable of programming cares about that feature, in most cases, or, that the software itself doesn't support it internally.
check on a site like here to make sure you didn't miss anything, and that actually that feature does exist somewhere somehow. If your results are negative again, that's about the end of the road in the quest for that personal favorite feature.
Check to see if there is another way that sort of emulates what you want. In this case, for example, you can go offline/online though it takes a few steps each time, and certainly isn't a feature intended to do what the OP asked, but it can be used in this way crudely.
If neither 1 nor 2 show support for the desired feature, decide how important that feature was to you. If it is very important, research the core codebase and see if you can extend it via extension to support the feature, or hire someone to write the extension for you, and maintain it over years, or don't use the software.
Now, if after these checks, you find that not one single person in the world cared enough to add support for the feature, it means there's not a whole lot of demand for it, and certainly no demand from the free software developers who in the case of thunderbird, wrote it, and its extensions, and probably not from the users either, which is a lot of people globally in this case.
Once you determine that there was and is no demand for the feature, move on to something more productive, and stop complaining that the feature that apparently nobody ever was willing to take the time to implement isn't implemented, it means nobody cared enough to do it, that's all. Complaining here about that won't change that fact.
If you have decided to use the new software anyway, then adjust your workflow to the fact that the desired feature is not going to be part of your life anymore. This is also known as being an adult in some societies.
Other similar things that don't support everything that another similar software does:
And so on. The software I write does similar things to other software, but is different, quite different, from all of them. This is why people use it and like it. If it were the same, there would be no reason to use it. If someone posts an issue asking for a feature a similar but different piece of software has, I'd think: Ok, is it a good idea? Does it meet a valid need? If so, is it hard? Is it possible at all (the other software may not even be right for example)? Is it possible within my software's framework? Did I receive a patch (always a great way to motive a developer)? If the first condition, it being a good idea, was never met, then you can forget about the rest, they are irrelevant.
I agree this isn't a great stackoverflow question.