Redmine Update Reminder:

This plugin sends reminder email to assigned users if an issue is not updated within specified duration.

Functionality:

All the mails are cc'ed to a single Group (generally scrum master/HR) along with the assigned user for notifying that a given task needs updation.
The duration for each kind of tracker can be set in settings. Duration takes input in days, and can be decimal point numbers (for instance .5 for 12 hours). Emails Headers and Footers are configurable for personalization.

Installation:

The plugin is available for download from github.com:arkhitech/redmine_update_reminder

Go to redmine's plugins directory and wheneverize the downloaded redmine_update_reminder plugin directory. Open config directory and edit schedule.rb

for example:

set :environment, "production"
every 1.day do
rake "redmine_update_reminder:send_user_reminders"
end 

This will check for all issues that have not been updated in the specified duration by the user and send them email.

Check whenever gems documentation for detailed description of its working.

There are two rake tasks. These can be run without scheduling using this command

RAILS_ENV=production rake redmine_update_reminder:send_issue_reminders

RAILS_ENV=production rake redmine_update_reminder:send_user_reminders