Enum SmtpOp 

#[non_exhaustive]
pub enum SmtpOp {
    Greeting,
    Ehlo,
    StartTls,
    AuthPlain,
    AuthLogin,
    AuthXOAuth2,
    AuthOAuthBearer,
    AuthScramSha256,
    MailFrom,
    RcptTo,
    Data,
    Quit,
}

The SMTP operation that was in progress when an error was observed.

This is the granularity an operator looks for in a log message: “MAIL FROM was rejected” is more useful than “the server returned 550”. Each variant corresponds to one user-visible step of the SMTP state machine.

The enum is non_exhaustive so that future SMTP extensions (e.g. AUTH XOAUTH2) can add a variant without forcing a major version bump.

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.

Greeting

Reading the server’s initial greeting (a 2xx line, typically 220).

Ehlo

EHLO and the capability negotiation that follows.

StartTls

STARTTLS command and the 220 reply that precedes the TLS handshake (RFC 3207).

AuthPlain

AUTH PLAIN (RFC 4616) initial-response exchange.

AuthLogin

AUTH LOGIN exchange (any of its three round-trips).

AuthXOAuth2

AUTH XOAUTH2 exchange (Google / Microsoft OAuth 2.0 SASL profile).

AuthOAuthBearer

AUTH OAUTHBEARER exchange (RFC 7628, IETF-standard OAuth 2.0 SASL mechanism).

AuthScramSha256

AUTH SCRAM-SHA-256 exchange (RFC 5802 / RFC 7677). Available only with the scram-sha-256 cargo feature; the variant itself is always present for source-compatibility stability.

MailFrom

MAIL FROM:<...> envelope-sender announcement.

RcptTo

RCPT TO:<...> recipient announcement (any of several when the message has multiple recipients).

Data

The DATA command and the body that follows it.

Quit

QUIT shutdown handshake.

Implementations

impl SmtpOp

pub const fn as_str(self) -> &'static str

A short, on-the-wire-style label for this operation. The string matches the SMTP command keyword whenever there is one ("MAIL FROM", "DATA", "AUTH PLAIN"); for the greeting (which is server-initiated) the label is "greeting".

Trait Implementations

impl Clone for SmtpOp

fn clone(&self) -> SmtpOp

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for SmtpOp

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

Formats the value using the given formatter.

impl Display for SmtpOp

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

Formats the value using the given formatter.

impl Hash for SmtpOp

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for SmtpOp

fn eq(&self, other: &SmtpOp) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for SmtpOp

impl Eq for SmtpOp

impl StructuralPartialEq for SmtpOp