Enum MailEvent 

#[non_exhaustive]
pub enum MailEvent {
    Delivered {
        message_id: String,
        recipient: String,
    },
    Deferred {
        message_id: String,
        recipient: String,
        attempt: u32,
    },
    Bounced {
        message_id: String,
        recipient: String,
        code: u16,
        reason: String,
    },
    Received {
        message_id: String,
        from: String,
        mailbox: String,
    },
}

A lifecycle event emitted by the engine.

Marked #[non_exhaustive]: new variants will appear as the engine grows, and consumers must keep a catch-all arm.

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.

Delivered

An outbound message was accepted by the remote server (250 to our DATA). Responsibility has transferred.

Fields

message_id: String

Engine-assigned identifier of the message.

recipient: String

The recipient this delivery was for.

Deferred

The remote server said “not now” (4xx). The message stays queued and will be retried with backoff — this is normal email behavior, not an error (greylisting relies on it).

Fields

message_id: String

Engine-assigned identifier of the message.

recipient: String

The recipient whose delivery was deferred.

attempt: u32

Which delivery attempt this was (1-based).

Bounced

The remote server said “no, permanently” (5xx), or the queue lifetime expired. A bounce is generated toward the envelope MAIL FROM.

Fields

message_id: String

Engine-assigned identifier of the message.

recipient: String

The recipient that could not be reached.

code: u16

The SMTP status code that ended the attempt.

reason: String

The remote server’s human-readable reason line.

Received

An inbound message was accepted and stored.

Fields

message_id: String

Engine-assigned identifier of the message.

from: String

The envelope sender it arrived with.

mailbox: String

The local mailbox it was delivered to.

Trait Implementations

impl Clone for MailEvent

fn clone(&self) -> MailEvent

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for MailEvent

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

Formats the value using the given formatter.