Hi!
I have some problem here.
There are 3 groups of users in nagios. Let’s call them Group 1, Group 2 and Group 3.
I need Nagios to send an email to Group 1.
Then, 30 minutes after the problem occur, it must send an email to Group 2.
Then, 1 hour after the problem occur, the email is sent to Group 3.
Then, if the problem is still not solved, the email is sent to all 3 Groups every hour.
Is it possible?
Well… I don’t think you can do it with nagios options; so you will have to use event_handler to do that
you can find more info on this on the nagios doc 
Thank you!