cannot be sure about who will be notified about changes to a bug

I suggest that this is Won't Fix.

The only way we can know if the "May be notified" people will receive a notification is to see what change you make. If you change a tag that someone is following, or change a status that someone is filtering on, or do any number of other changes, *then* (of course) we can determine retroactively who should find out. We can't determine who will be notified because we can't predict the future.

Options to address this that I see fitting in with the necessary constraints are two:

- Remove the "May be notified" listing entirely. My memory is that user tests showed that it was appreciated, so I don't advise this option.

- Consider enabling a "whom did I notify" functionality, that gave you information after you performed a task. We talked about this when making the associated changes. It has technical problems--we calculate the full set of people who are notified asynchronously--and, to our minds, very limited value.

So "may be notified" means "subscribed, but with filters?"

Yes, that is what it means. I concur with Gary that won't fix would be ok from a project perspective. However, it is true that you cannot be sure, so leaving this as triaged-low makes quite a bit of sense: after all, if someone were to provide a patch that would tell you after the fact who was notified, that would be pretty nice to have.

So, I think I made some confusion here. I didn't notice that some bugs (like this one) also have a list of people who are "Notified of all changes", I thought that "May be notified" were the only list available.

This is a useful bug, because if you are mystified by the feature and google 'launchpad "may be notified"' it's the first hit. When you comment on a bug, you may be curious to know how many people are going to be spammed. Apart from the ideas above, there are a couple of other things that could be done:

a) add a "?" icon beside "May be notified" which would give an explanation (as above) of what it means.

b) perhaps it would be possible to split it into multiple sections, such as "notified of comments" etc.