Would it be possible to not send the text in the spoiler tag when sending an email for a subscribed thread?

not sure we can edit specific content that gets sent in subscription emails..it's something Geoff would have to look

I was just about to start a new thread about this. Redinger, was this prompted by a reveal of a plot twist in 15 Minutes?

No, it happens all the time in the Lost threads. It's only an issue when someone posts spoiler info about episodes that haven't aired yet in older threads.