The example hook in this repository contains an example of integration with driusan/dkim tools, and assumes the following:
- The selector for a domain
can be found in the file
- The private key to use for signing can be found in the file
Only authenticated email will be signed.
Verifying signatures is technically supported as well, and can be done in the same hook. However, it's not recommended for SMTP servers to reject mail on verification failures (source 1, source 2), so it is not included in the example.