Send a 'thank you' email to your blog's commenters.
No. The default settings are generic. You should take time to write a message which offers some value -- for example, you may ask people to join you on Twitter or offer them a discount on their next purchase.
When writing your message, look under 'Schedule'. Set 'Maximum send limit' to 1. It is strongly recommended you make this change.
If you have recently installed Thank Me Later, please wait 12 hours. On some installations of WordPress, Thank Me Later is unable to schedule email sends correctly. Thank Me Later is able to detect this issue and will revert to "Legacy Mode" to send emails after 12 hours.
If emails are still not sending on time, your blog may not be receiving enough visits to send the emails -- emails are only sent on page loads. Possibly, caching is preventing the scheduled events from running. If you know what you are doing, you can create a cron job to call WP-Cron at regular intervals -- see here for more details.
This is by design. Emails are sent to all commenters, regardless of whether they are authors or readers. If the messages are annoying you, you probably haven't configured Thank Me Later correctly. Ensure you set 'Maximum send limit' to 1 to limit the number of emails that are sent to a particular commenter.