I also had a log source that sent related events in separate messages that were interleaved with other messages and ended up using the program() destination to send the logs to a custom handler I wrote.

Essentially I had multiple "keys" for incoming email messages that tied events together like:

- a single incoming SMTP session (potentially with multiple messages)

- a single message ID with multiple events about the message (recipients, attachments, anti-malware, etc)

- a single delivery connection (again with multiple messages)

- a single delivery message ID again with multiple events

The program parsed these in realtime incoming stream, building internal data structures (hash of hashes) and when it looked *complete* (including a timeout) for a particular thing it would send the data across as JSON to the destination (Elasticsearch in this case)

So - long answer to your question - Yes - in a few different ways :-)

Best,

Jim