Proxies web-api messages to smtp emails so apps don't have to mess with SMTP. Just fire api messages to the AppMailRelay, and let it worry about SMTP.
A typical scenario is where you've got apps running in various clouds, but want to pipe email messages back to your on-premissis mail server. So you run AppMailRelay on-prem, and any distributed apps send messages via web-requests to it's API. In turn, the AppMailRelay sends those message to the on-prem mail server via SMTP.
For apps that insist on talking SMTP, you can host an instance of AppSmtpRelay, which accepts SMTP messages and relays them to your on-prem AppMailRelay. The AppSmtpRelay is dumb, no auth, etc.; designed for accepting traffic from the local network, so don't expose it publicly.
Run the application (dotnet AppMailRelay.dll) to start proxying messages between clients and a mail server.
See the src/AppMailRelay/appsettings.json for settings.
Add client keys to the Relay:ClientKeys array in the form of client-name#randomsecret.
When running the docker image, mount a custom appsettings.Production.json into /app. Or set environment variables à la AspNetCore.
The API is pretty simple for clients; see the Readme for API documentation.
The AppMailClient is prebuilt to drop in to an app. See the Readme.
This project relies on the great work of these projects: