Mandrill is a Transactional Email Service. If you are using it you might be interested in monitoring statistics they are offering via their API
This tool helps you doing this when you are using Prometheus as monitoring system. It is an exporter that runs as a standalone application and can be scraped by prometheus.
It is recommended to use the exporter with Docker.
docker run -p 9153:9153 -e "MANDRILL_API_KEY=<YOUR_API_KEY>" -d hypoport/mandrill-prometheus-exporter