Seq.App.EmailPlus 
In this repository you'll find Seq.App.EmailPlus: send log events and alerts as HTML email messages when they arrive at Seq.
Also from Datalust, elsewhere on GitHub:
- File Archive - write incoming events into a set of rolling text files
- First of Type - raise an event the first time a new event type is seen
- Replication - forward incoming events to another Seq server
- Thresholds - raise an event if the frequency of matched events exceeds a threshold
- Digest Email - send multiple events as a single HTML email
- Health Check Input - periodically GET an HTTP resource and write response metrics to Seq
- GELF Input - ingest events GELF format over TCP or UDP
- JSON Archive - write incoming events into a set of rolling files, in JSON format
- RabbitMQ Input - ingest events from RabbitMQ
- Syslog Input - ingest syslog events over UDP