Enum MailerError 

#[non_exhaustive]
pub enum MailerError {
    ConfigurationMissing(String),
    Transient(String),
    Permanent(String),
}

Errors a Mailer can return. The most important variant is MailerError::ConfigurationMissing — the framework treats it as a hard boot failure when production deployments forget to wire up a real mailer (per the user-locked decision: “Mailer blocking behaviour” → refuse to start when no mailer is configured for production).

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

ConfigurationMissing(String)

The mailer is structurally missing — no transport, no API key, etc. R1+ boot guards check for this at startup.

Transient(String)

A transient failure (SMTP timeout, 5xx from the API, queue full). Recovery flows treat this as “log + uniform user response” per the user-locked mailer-blocking-behaviour decision: the user sees the same response as success; an audit row is written with metadata.email_send_status = "failed" so the operator can grep for undelivered resets.

Permanent(String)

A non-recoverable failure (invalid recipient, blocked domain). Surfaces in audit logs the same way as Transient.

Trait Implementations

impl Debug for MailerError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for MailerError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Error for MailerError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.