The stock "Send Email" action type that ships with Drupal 6 does't offer a whole lot of options for including content from comments in your triggered emails.

In fact, it doesn't offer any.

There has been a good deal of discussion on this: a patch has been proposed and a stop-gap helper module has been posted to drupal.org.

Before you go that route, though, check out this post on using the Token Actions module to provide access to the full array of available tokens in your email. Thanks to Erik Weik at New Rivers Digital for the great post.

We're using Trigger-based email notifications to fight spam and help our clients be engaged with their commenters.

How do you use and implement comment notifications?