Notifications when the SLA is near the end

When the SLA tasks is near the end, we have two situations:

1 The SLA starts to turn yellow and alerts users that the end is near;

2 The SLA starts to turn red when about to maxing;

The idea would be to send email notifications to users who are following the issue. In the same style of default JIRA notifications, a notification of SLA terms for a group of people we want.

We have a vision without worries of issue by issue, alerting us whenever any issue is near the end. Because not always users are following all SLA's.