As a Jira Admin I would like to have Health Check for outgoing mail queue

Problem Definition

Jira has a Queue for outgoing messages. Sometimes the queue can grow significantly for many reasons, leading to delayed email notifications.

Usually, Jira admin will know about those problems from end-users, which is too late.
To prevent this, Jira Admin needs to open the Mail Queue page for each individual node and check the status of the Queue.

Suggested Solution

Introduce a new Health Check (HC) in ATST plugin that will check the healthiness of the mail queue on each node in DC.
We consider a mail queue healthy if the oldest email it contains is kept there for less than the time specified by the threshold (default 30 min).

Workaround

None