Implement Mail Handling Rules for Administrators

As an administrator, I would like to have the possibility to define different mail configurations and rules to handle mails/notifications. Among others:

• Possibility of enabling/disabling completely mail system
• Number of retries for delivering a message
• Automatic resend of a message after a certain time interval 
• Automatic purge of the message if it was not successfully delivered after X retries and after X time
• Receive an alert/notifications when X messages are accumulated on the ErrorQueue
• Possibility of setting a Max Message Size
• Be able to define global settings for Users notifications (as described in CONFSERVER-39970)
• Add some capabilities to the Error Queue (as described in CONFSERVER-3231)