Crate missive 

Missive

Compose, deliver, and test emails in Rust. Plug and play.

Quick Start

Create a client and pass it through your application state:

use missive::{Email, EmailClient};
use missive::providers::ResendMailer;

let mailer = ResendMailer::new(std::env::var("RESEND_API_KEY")?);
let client = EmailClient::new(mailer)
    .with_default_from("noreply@example.com");

let email = Email::new()
    .to("user@example.com")
    .subject("Welcome!")
    .text_body("Hello");

client.deliver(email).await?;

The legacy deliver(&email) global facade remains available for small apps and compatibility, but EmailClient is the primary API. For explicit environment loading, use EmailClient::from_env().

Multiple Clients

use missive::{Email, EmailClient};
use missive::providers::ResendMailer;

let transactional = EmailClient::new(ResendMailer::new("transactional_key"))
    .with_default_from("receipts@example.com");
let marketing = EmailClient::new(ResendMailer::new("marketing_key"))
    .with_default_from("news@example.com");

transactional.deliver(receipt_email).await?;
marketing.deliver(newsletter_email).await?;

Environment Variables

Variable	Description
EMAIL_PROVIDER	smtp, resend, unsent, postmark, sendgrid, brevo, mailgun, amazon_ses, mailtrap, mailjet, socketlabs, gmail, protonbridge, jmap, logger, logger_full
EMAIL_FROM	Default sender email
EMAIL_FROM_NAME	Default sender name
SMTP_HOST	SMTP server host
SMTP_PORT	SMTP server port (default: 587)
SMTP_USERNAME	SMTP username
SMTP_PASSWORD	SMTP password
SMTP_TLS	SMTP TLS mode: starttls (default), tls, or none
RESEND_API_KEY	Resend API key
UNSENT_API_KEY	Unsent API key
POSTMARK_API_KEY	Postmark API key
SENDGRID_API_KEY	SendGrid API key
BREVO_API_KEY	Brevo API key
MAILGUN_API_KEY	Mailgun API key
MAILGUN_DOMAIN	Mailgun sending domain
AWS_REGION	AWS region for SES
AWS_ACCESS_KEY_ID	AWS access key
AWS_SECRET_ACCESS_KEY	AWS secret key
MAILTRAP_API_KEY	Mailtrap API key
MAILTRAP_SANDBOX_INBOX_ID	Mailtrap sandbox inbox ID (optional)
MAILJET_API_KEY	Mailjet API key
MAILJET_SECRET_KEY	Mailjet secret key
SOCKETLABS_SERVER_ID	SocketLabs server ID
SOCKETLABS_API_KEY	SocketLabs API key
GMAIL_ACCESS_TOKEN	Gmail OAuth2 access token
PROTONBRIDGE_USERNAME	Proton Bridge SMTP username
PROTONBRIDGE_PASSWORD	Proton Bridge SMTP password
PROTONBRIDGE_HOST	Proton Bridge host (default: 127.0.0.1)
PROTONBRIDGE_PORT	Proton Bridge port (default: 1025)
JMAP_URL	JMAP server URL
JMAP_USERNAME	JMAP username (for basic auth)
JMAP_PASSWORD	JMAP password (for basic auth)
JMAP_BEARER_TOKEN	JMAP bearer token (for OAuth2)

Feature Flags

• smtp - SMTP provider via lettre
• resend - Resend API provider
• unsent - Unsent API provider
• postmark - Postmark API provider
• sendgrid - SendGrid API provider
• brevo - Brevo API provider (formerly Sendinblue)
• mailgun - Mailgun API provider
• amazon_ses - Amazon SES API provider
• mailtrap - Mailtrap API provider (testing/staging)
• mailjet - Mailjet API provider
• socketlabs - SocketLabs Injection API provider
• gmail - Gmail API provider (OAuth2)
• protonbridge - Proton Bridge provider (local SMTP)
• jmap - JMAP protocol provider (Stalwart, Fastmail, etc.)
• local - LocalMailer for development and testing
• preview - Mailbox preview web UI
• metrics - Prometheus-style metrics (counters/histograms)
• dev - Enables local and preview

Metrics

Enable features = ["metrics"] to emit Prometheus-style metrics:

Metric	Type	Labels	Description
missive_emails_total	Counter	provider, status	Total emails sent
missive_delivery_duration_seconds	Histogram	provider	Delivery duration
missive_batch_total	Counter	provider, status	Total batch operations
missive_batch_size	Histogram	provider	Emails per batch

Install a recorder (e.g., metrics-exporter-prometheus) in your app to collect them.

Re-exports

pub use interceptor::Interceptor;

pub use interceptor::InterceptorExt;

pub use interceptor::WithInterceptor;

Modules

interceptor

Email interceptors for modifying or blocking emails before delivery.

prelude

Prelude module for convenient imports.

providers

Email provider implementations.

Structs

Address

An email address with an optional display name.

ApiKeyConfig

Configuration for providers that require one API key.

Attachment

An email attachment.

DeliveryResult

Result of a successful email delivery.

Email

An email message.

EmailClient

Instance-owned email client.

PreparedEmail

An email that has passed Missive’s shared delivery validation.

Enums

AttachmentType

Type of attachment disposition.

MailError

Errors that can occur when sending emails.

MailerConfig

Typed configuration for building a mailer from environment-like input.

Constants

VERSION

The version of the missive crate.

Traits

Mailer

Trait for email delivery providers.

ToAddress

Trait for types that can be converted to an email address.

Functions

configure

Manually configure the global mailer.

configure_arc

Configure with an Arc’d mailer.

default_from

Get the default from address from environment.

deliver

Deliver an email using the global mailer.

deliver_many

Deliver multiple emails using the global mailer.

deliver_with

Deliver an email using a specific mailer (per-call override).

init

Initialize the mailer from environment variables.

is_configured

Check if email is configured (env vars are set and feature is enabled).

mailer

Get a reference to the configured mailer (if initialized).

reset

Reset the global mailer (useful for tests).