Struct MessageBuilder 

pub struct MessageBuilder { /* private fields */ }

Builder for outbound RFC 5322 messages.

Construction is chain-style: MessageBuilder::new().from(..).to(..).subject(..). Call build for the raw bytes or use the [Display] impl for a UTF-8 string view.

Implementations

impl MessageBuilder

pub fn new() -> Self

Empty builder. All fields default-empty.

pub fn from(self, addr: impl AsRef<str>) -> Self

Set From: (single mailbox).

pub fn reply_to(self, addr: impl AsRef<str>) -> Self

Set Reply-To: (single mailbox).

pub fn to(self, addr: impl AsRef<str>) -> Self

Append one To: recipient.

pub fn cc(self, addr: impl AsRef<str>) -> Self

Append one Cc: recipient.

pub fn bcc(self, addr: impl AsRef<str>) -> Self

Append one Bcc: recipient. Bcc is emitted into the message body so a downstream MTA strips it before relay; callers emitting via the SMTP envelope should NOT add the bcc here.

pub fn subject(self, s: impl Into<String>) -> Self

Set Subject:. Non-ASCII values are RFC 2047 encoded.

pub fn date(self, s: impl Into<String>) -> Self

Set Date:. If omitted, build() fills in the current UTC in RFC 5322 §3.3 format.

pub fn message_id(self, s: impl Into<String>) -> Self

Set Message-ID:. Must include the angle brackets (e.g. <abc@example.com>).

pub fn text_body(self, s: impl Into<String>) -> Self

Set the text/plain body.

pub fn html_body(self, s: impl Into<String>) -> Self

Set the text/html body. If both text_body and html_body are set, the message becomes multipart/alternative.

pub fn attachment(self, att: Attachment) -> Self

Append an attachment. Adding any attachment promotes the message to multipart/mixed.

pub fn header(self, name: impl Into<String>, value: impl Into<String>) -> Self

Add an arbitrary extra header. Use sparingly — almost every standard header has a typed setter above. Header values are folded and encoded-word-protected automatically.

pub fn report_type(self, kind: impl Into<String>) -> Self

Set the multipart report-type per RFC 6522. With this set, any multipart container the builder emits uses multipart/report; report-type=<value>; boundary=... instead of multipart/mixed. Required for DSN (report_type("delivery-status")), MDN (report_type("disposition-notification")), and TLSRPT (report_type("tlsrpt")).

pub fn build_strict(&self) -> Result<Vec<u8>, LintError>

Render the message to raw bytes after running the strict-mode invariant checks. Returns the first failure if any.

Use this when you want compile-time-level confidence that the outbound bytes meet RFC 5322 / 2045 invariants — e.g. before handing them to a DKIM signer that would silently sign a non-compliant message, or before publishing them as a stalwart-grade artifact in a corpus.

pub fn build(&self) -> Vec<u8>

Render the message to raw bytes.

Trait Implementations

impl Clone for MessageBuilder

fn clone(&self) -> MessageBuilder

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for MessageBuilder

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

Formats the value using the given formatter.

impl Default for MessageBuilder

fn default() -> MessageBuilder

Returns the “default value” for a type.

impl Display for MessageBuilder

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

Formats the value using the given formatter.