For emailed comment notifications, I still support including the whole comment, but with the warning prominently on top, and perhaps scroll space / a bit of null content so that if someone wanted to stop right there they'd be able to.

And I hadn't even considered what should be done with emailed notifications for *replies* to the comment, because there would be cases where people other than the comment poster would be getting those email replies, and the original comment is included along with the thing. (Cases include: any time someone who would have already read it once might not welcome stumbling across it again in their inbox; where the person replying is not the entry owner and the entry owner gets another copy, where the person replying gets notifications of their own comments, if someone not participating in the discussion has subscribed to the thread, individual entry, or all comments to the community.)