Collect end-to-end mail statistics in SQL

[Paul Everitt]

We currently store stuff in Redis via logger entries. We probably are going to want rich queries. We can keep Redis for the current logging. But for the stats we want to make in the new distribution list monitoring UI, we might want stuff in SQL.

Which would also mean some self-managing way to avoid filling up the database.

[Carlos de la Guardia (cguardia)]

Instead of SQL, the plan is to push logging info to graylog, then use its extractors, dashboards, and alerts to process it.