When going from one email folder to another, sometimes you get the wrong emails listed.
Instead of the emails of the fresh opend folder you get the emails of the previously visited one.

When trying to open one of these you naturally get an error, because the requested email doesn't exist in this folder.

This seems to be a race condition.
Because when you get it, there is always an automatic reload of the list in background at the same time. Or you have to switch folders very fast.

I assume the automatic reload answer is handed over to the opening folder query.