> For the complete documentation index, see [llms.txt](https://quantumphp.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://quantumphp.gitbook.io/docs/packages/mailer/overview.md).

# Overview

The Mailer package gives Quantum a shared mail-sending entry point with one SMTP transport and several API transports.

Use it when you want to build an email with `mailer()`, choose a configured delivery adapter, and send either a raw HTML body or a PHP template.

## When to use it

Reach for Mailer when you need to:

* send application emails through the configured default provider
* switch between SMTP and provider APIs without changing the calling code
* render email bodies from a PHP template file
* save outgoing messages to the local mail trap instead of sending them

If you only need to inspect saved `.eml` files, use `MailTrap` directly. The Mailer package is the sending layer.

## Package shape

The package is built from a few small parts:

* `Quantum\Mailer\Mailer` is the proxy object returned by `mailer()`
* `Quantum\Mailer\Factories\MailerFactory` resolves and caches one mailer per adapter name
* adapters implement `Quantum\Mailer\Contracts\MailerInterface`
* `Quantum\Mailer\Traits\MailerTrait` provides the shared message-building and reset behavior
* `Quantum\Mailer\MailTrap` saves and parses local `.eml` files when mail trapping is enabled

## Supported adapters

Mailer supports these adapter names:

* `smtp`
* `mailgun`
* `mandrill`
* `sendgrid`
* `sendinblue`
* `resend`

The factory resolves the requested adapter or `mailer.default` when you do not pass one.

## Common message flow

All adapters share the same base flow:

1. set the sender with `setFrom()`
2. add one or more recipients with `setAddress()`
3. optionally set a subject
4. provide either `setBody()` or `setTemplate()` with message data
5. call `send()`

After `send()` finishes, the package clears the sender, recipients, subject, body, and template from the adapter instance.

## Important constraints

* `MailerFactory` caches one `Mailer` instance per adapter name inside the shared factory service.
* Adapter-specific methods are available only when the underlying adapter implements them.
* Only the SMTP adapter supports reply-to, CC, BCC, and attachments.
* Template paths are stored without the `.php` suffix. The package always requires `<template>.php`.
* `send()` returns `false` on transport failure and logs transport errors to the debugger mails tab through `warning(...)`.
* Message IDs can be reused across sends in long-running processes, so do not assume every send gets a fresh generated message ID automatically.
* When `mailer.mail_trap` is enabled, the package saves a local `.eml` file instead of contacting the transport.


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