Enum Error 

#[non_exhaustive]
pub enum Error {
    EmptyInput,
    MissingFrom,
    InvalidDate(String),
    InvalidAddress(String),
    MissingSender,
    InvalidHeaderName(String),
    InvalidMessageId(String),
    HeaderLineTooLong(String),
    ReservedHeaderName(String),
    InvalidAttachment(String),
    InvalidTraceHeader(String),
    InvalidResentHeader(String),
}

Errors that can occur during email message parsing or building.

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.

EmptyInput

Empty input provided to the parser (RFC 5322 Section 3.5 — a valid message must contain at least header fields, so zero bytes is invalid).

MissingFrom

Missing required From header (RFC 5322 Section 3.6.2).

InvalidDate(String)

Date header could not be parsed per RFC 5322 Section 3.3.

InvalidAddress(String)

Syntactically invalid email address (RFC 5322 Section 3.4).

MissingSender

Missing Sender header when From has multiple addresses (RFC 5322 Section 3.6.2).

RFC 5322: “If the from field contains more than one mailbox specification in the mailbox-list, then the sender field, containing the field value corresponding to the responsible agent of the message MUST be present in the message.”

InvalidHeaderName(String)

Invalid header field name (RFC 5322 Section 2.2).

The name is empty, contains non-ftext characters, or is otherwise malformed per RFC 5322 Section 2.2 (field-name = 1*ftext).

InvalidMessageId(String)

Invalid message-ID (RFC 5322 Section 3.6.4).

The value is empty, missing the @ separator, contains prohibited characters, or has empty id-left / id-right parts.

HeaderLineTooLong(String)

A header value contains a token or whitespace run that cannot be folded within the 998-octet line limit (RFC 5322 Sections 2.1.1, 2.2.3).

ReservedHeaderName(String)

An extra_headers entry uses a field name reserved for standard headers managed by the builder (RFC 5322 Section 3.6).

InvalidAttachment(String)

An attachment violates MIME constraints — invalid content encoding, missing required headers, or prohibited bytes (RFC 2045/2046).

InvalidTraceHeader(String)

A trace header (Return-Path / Received) violates RFC 5322 Section 3.6.7 syntax or cardinality rules.

InvalidResentHeader(String)

A Resent-* header violates RFC 5322 Section 3.6.6 syntax, cardinality, or block-grouping rules.

Trait Implementations

impl Clone for Error

fn clone(&self) -> Error

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Error

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

Formats the value using the given formatter.

impl Display for Error

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

Formats the value using the given formatter.

impl Error for Error

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.

impl PartialEq for Error

fn eq(&self, other: &Error) -> 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 Eq for Error

impl StructuralPartialEq for Error