If all selected, all will run. There is also on some projects the option to allow non-selected applications to run if none of selected ones available.

In all the projects I use, there's "run only the selected applications" in the preferences. I can't find any explanation as to what this would do if you deselected all of them. Would it allow all to run, or none?

Not allowed, at least one must be ticked.

I just tried it on Amicable numbers, and it automatically reselected them all, after stating "all applications" in the non-editing screen of the preferences.

That's the answer to your question.

So not sure what would happen if a new application was brought out - would it default to being ticked? What I'm trying to do is tell it to run any application the project wants, including future ones.

To add confusion some projects have a "allow test applications." If there is a test application tick you have to select that to allow test applications to run. When the project admin adds a new application, he decides if that will be auto given to everyone or if everyone has to go to their preferences page and change it.

In some projects this is worded "if no work available for selected applications run others" which is self explanatory. For what you want to do don't select the "run only" and it will allow work for any. But understand if you have ticked one app as long as there is work for that app, that is the only one that will run.

It's probably the settings on their webpage.
You'll be notified when you've subscribed to their newsletters.
If not, then you'll have to check regularly, to see which be projects are added.
Like for instance, IBM just added an 'africa rainfall' project.
If you don't prefer to crunch for that cause, it might be best to just leave it deselected, and crunch for the other causes of this group.

It's probably the settings on their webpage.
You'll be notified when you've subscribed to their newsletters.
If not, then you'll have to check regularly, to see which be projects are added.
Like for instance, IBM just added an 'africa rainfall' project.
If you don't prefer to crunch for that cause, it might be best to just leave it deselected, and crunch for the other causes of this group.

I don't think I've ever been asked to subscribe to a newsletter. For example on Einstein, the closest I can find is:
https://einsteinathome.org/account/prefs/privacy
"Is it OK for Einstein@Home and your team (if any) to email you?" which I've always had set to yes.

Oh well, if I ever don't get work for a project, I'd check the server status and find there's something else I should be subscribed to. But I'm assuming if it's an important project it would be set to ticked by default.

Every project has a newsletter; though not every project sends one out on a regular base.
There is an option to receive it via email, or in the client itself (the announcements).

About half way down this page, under "applications" - https://einsteinathome.org/account/prefs/project
Not as clear as for some projects, but you tick the ones you want to run (the default is all ticked).

You've changed subject yet again - I answered the initial question.

I'm fairly sure there's NO "newsletter"; it's a Notification, or in the BOINC Manager, a Notice.

The option for selecting which to use is on your account page, under Community preferences, the first section.

************************

And for climateprediction, they've made it easy, by removing the choose-a-task-type option.
Now, people are sent whatever is available for the OS of each of their computers.

Have a look at this page, it might be what you are looking for:
https://einsteinathome.org/account/prefs/privacy

(I have the options for Einstein to email me set true, but I can't recall any news letter type messages from them.)

At SETI, I see:

Is it OK for SETI@home and your team (if any) to email you?

It's in https://setiathome.berkeley.edu/prefs.php?subset=project. There isn't an actual 'newsletter', as such, but they do email many users once a year with a fundraising request (*), usually with a progress report.

It looks as if Einstein were preparing to do the same in https://einsteinathome.org/account/prefs/subscriptions, but never got round to it.

* not to users currently in the EU and subject to the GDPR.

In cpdn, it says: How should we notify you of new private messages, friend requests, posts in subscribed threads, and other events?

I assume that "other events" covers anything else that occurs.

Checked a couple of other projects, and it seems as if the

Is it OK for [project] and your team (if any) to email you?

formulation is part of the standard BOINC website template.

Oh my god, seriously?! The EU has forbidden SETI from asking us for donations? The EU needs to be shut down, now.

SETI - unlike some Americans - is operating with an excess of politeness. It's been on their front page since the end of November:

Because of our continued effort to be GDPR compliant, we're not sending emails to anyone with an EU/EAA email addresses, anyone who listed an EU/EAA country, or anyone who listed "International" as their country. And, of course, anyone who has opted out of our emails won't get them.

What has the EU ever done for us? Provided a spam filter. I am Spartacus.