I have my account configured so that I get email alerts when I am tagged in a post or someone replies to my comment/post. If they have some text in their post that is obscured by a spoiler tag, then it will simply appear as visible plaintext in the email update. You don't even know if something has been marked as a spoiler, because formatting has been removed.
What do you all think of this? Should there be a warning in the email update that there is a spoiler? Perhaps something like <spoiler>dumbledore dies</spoiler>? Or should it be blanked out completely?