A general implemetation question

Hi
    I am asking a general implementation question..I have two models
ServiceDeskTicket and ServiceDeskActivity.The service_desk_tickets table
has an updated_on field(one of magic field supplied by rails) which
carries the latest updated on time for the ticket.This field is updated
two ways
1.When updating a servicedesk ticket
2.when a new activity is added.
               I have to implement the following..If a service desk
ticket is inactive for 48 hours (inactive means if the update_on is
greater than 48 hours) then send a mail (to primary assignee of group).
              Which is the best way to implement this?I have a basic
idea that tom write a rake task and call it with a cronjob.(Am I
right?).But how?Suppose there are some thousands of service desk tickets
..So how to ensure mail send with in 48 hours for each of them if
inactive?
        Please help me to solve this problem
  Expecting your valuable comments

Sijo

I think you're on the right track with a rake task and cron.

To send large amount of emails, google ar_mailer