let res: DKIMResult = kumo_dkim::verify_email(&from_domain, &parsed_email).await?;

if let Some(err) = &res.error() {
  error!(logger, "dkim verify fail: {}", err);
}

println!("dkim={}", res.with_detail());

Signing an email

Example:

let private_key =
    rsa::RsaPrivateKey::read_pkcs1_pem_file(Path::new("./test/keys/2022.private"))?;

let signer = SignerBuilder::new()
    .with_signed_headers(["From", "Subject"])?
    .with_private_key(private_key)
    .with_selector("2020")
    .with_signing_domain("example.com")
    .build()?;
let signature = signer.sign(&email)?;

println!("{}", signature); // DKIM-Signature: ...

See the SignerBuilder object documentation for more information.

Generate a test DKIM key

Using OpenDKIM:

opendkim-genkey \
    --testmode \
    --domain=example.com \
    --selector=2022 \
    --nosubdomains