Do students receive announcement notifications after the last day of class?
This is a difficult question to answer. I want to say yes and am pretty sure that is correct. If the course get concluded however the answer is probably no. And in fact, if the class gets concluded you won't even be able to create an Announcement because the course becomes "read only" at that point.
The other unknown is how your system has been set up by admins. In some cases a course will get concluded automatically after the end date, but it also can be set to not do that. Again, my guess is that if you can still post an announcement the students should receive it.
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