Thank Me Later is a popular open source WordPress plugin that sends “thank you” emails to a blog’s commenters.
Time delay. The idea is to grab a commenter’s attention and bring them back to your blog. Sending an email straight away doesn’t make much sense. You can delay your message for a week (for example), and prompt commenters to return to your blog and further engage with conversation.
Personalisation. Include a commenter’s name, comment or post title in your email message for a more personal touch. ‘Sarah, thank you for your comment on My Cool Web Links’ is more noticeable than ‘Thank you for your comment’.
Targeting. Create targeted emails for categories or specific posts on your blog. Targeted emails are a great way to make email messages more relevant to the user, and makes them more likely to return to your blog.
HTML emails. Send beautiful HTML emails to your commenters.