In addition to the overall queue totals exiqsumm provides a breakdown by destination domain. It would be nice to have labels representing this, or perhaps a subset of domains. e.g. it would be useful to see the number of deferred messages specifically to wikimedia.org addresses.

Removing SRE, has already been triaged to a more specific SRE subteam

The mail dashboard has already a quick display of the queues, I've added a graph to see both frozen and unfrozen queues.
As for the breakdown by domain that will need to be added to the prometheus exporter (using something like exim -bp | exiqsumm -c | head -n 12) and I'll leave it to @jhathaway to decide if it's needed or not.

Let me note that we also have an alert on exim_queue_length per https://gerrit.wikimedia.org/r/plugins/gitiles/operations/alerts/+/refs/heads/master/team-sre/mail.yaml#17. Severity is page, so we should be ok from that side. I am not sure per domain breakdown actually helps in a graph, but that's just my 2 cents.

I am inclined to say we resolve this for what is worth.