I know, and it’s obvious that if the user has seen the post, no email should be sent, i.e. seeing the post cancels email. But my suspicion is that being linked to in topic also cancels the user watching email, probably because we don’t want to email about the same post twice.
If this is indeed what is happening, then my suggestion is that instead of sending the “you have been linked email” we should send the email “there is a new topic in the category you’re watching”.
Not at the moment. And only if we agree that this is not expected behaviour. But that is implied in your question, right?