Function deltachat::authres::handle_authres

pub(crate) async fn handle_authres(
    context: &Context,
    mail: &ParsedMail<'_>,
    from: &str,
    message_time: i64
) -> Result<DkimResults>

authres is short for the Authentication-Results header, defined in https://datatracker.ietf.org/doc/html/rfc8601, which contains info about whether DKIM and SPF passed.

To mitigate From forgery, we remember for each sending domain whether it is known to have valid DKIM. If an email from such a domain comes with invalid DKIM, we don’t allow changing the autocrypt key.

See https://github.com/deltachat/deltachat-core-rust/issues/3507.