We recently started using smtp4dev:
https://github.com/rnwood/smtp4dev
I found it quickly after coming to the realization that a "mailtrap" for local development was very likely a solved problem.
It took 15 minutes and 10 lines of code to add it to the current project's docker-compose-file and so far it's working great. I love how easy docker/podman makes it to set up such services.