brotherhood_of_LAN - 4:07 pm on May 16, 2013 (gmt 0)
But with enough records I know this will be very inefficient. When a visitor saves a comment, it will take a long time to send all emails before returning.
I assume you are not doing the mailing process as part of the new comment submission logic, i.e. the confirmation page of the newest poster.
Create a mail queue table and run a cron job to deal with the mailing that way.