//! Outbound delivery: smarthost relays and direct-to-MX.
//!
//! Two paths behind one interface:
//!
//! - **relay** — hand the message to SES / OCI Email Delivery / any smarthost
//!   on submission (587). Someone else's IP reputation. Works everywhere,
//!   including hosts that block outbound :25.
//! - **direct** — resolve MX, apply [`mail_mta_sts`] and [`mail_dane`], deliver
//!   ourselves. Our reputation, our control, and impossible on a host that
//!   blocks outbound :25 (see `docs/adr/0005-oracle-cloud.md`).

pub mod providers;

pub use providers::{PROVIDERS, RelayProvider, provider, resolve_host, spf_include};

#[derive(Debug, thiserror::Error)]
pub enum Error {
    #[error("no usable MX for {0}")]
    NoMx(String),
    #[error("relay rejected: {code} {text}")]
    Rejected { code: u16, text: String },
    #[error("TLS policy violation: {0}")]
    TlsPolicy(String),
    #[error("transient failure, retry: {0}")]
    Transient(String),
}