#[derive(Debug, thiserror::Error)]
pub enum Error {
#[error("empty input: no message bytes provided")]
EmptyInput,
#[error("missing required From header (RFC 5322 Section 3.6.2)")]
MissingFrom,
#[error("invalid date: {0}")]
InvalidDate(String),
#[error("invalid email address: {0}")]
InvalidAddress(String),
#[error("build error: {0}")]
Build(String),
}