[exim] Monitoring and Reporting Eximstats

Hi,

I'd like to know what possibilities there are to get data about exim's
performance, irregularities, statistics, etc.

There are some obvious ways like monitoring if the process runs, if
there are old mail in the queue, crawling logs (mainlog, rejectlog,
etc). More advanced ways might be to analyze the spool directories,
maybe the dbs (retrydb, etc.).

I couldn't find anything that directly reports statistics for example
about fails without crawling the logs as eximstats does. There is a
Prometheus exporter, though it also just craws logs.
Is there a more direct approach to get statistics directly from exim
(which might then be exported to be used by Prometheus for example)?

I'd like to hear about what techniques you use to monitor your setups,
especially with setups beyond one or two mail servers.

Thanks in advance,
Christian