---
title: process.action_mailer
description: Rails generated an Action Mailer message.
url: https://docs.honeybadger.io/insights/event-types/ruby/process.action_mailer/
---

Rails generated an Action Mailer message.

Source **Action Mailer** Category **Mail** Fields **18** [honeybadger-ruby](https://docs.honeybadger.io/lib/ruby/)

## Fields

| Field                  | Type           | Description                                                                                                            |
| ---------------------- | -------------- | ---------------------------------------------------------------------------------------------------------------------- |
| `event_type`           | string         | Allowed value: `process.action_mailer`.                                                                                |
| `mailer`               | string         | Mailer class name, e.g. "UserMailer".                                                                                  |
| `action`               | string         | Mailer action method, e.g. "welcome\_email".                                                                           |
| `message_id`           | string         | Message-ID header of the generated email.                                                                              |
| `subject`              | string         | Email subject line.                                                                                                    |
| `to`                   | array\<string> | Recipient addresses.                                                                                                   |
| `cc`                   | array\<string> | CC addresses.                                                                                                          |
| `bcc`                  | array\<string> | BCC addresses.                                                                                                         |
| `date`                 | string         | Email date header as a string.                                                                                         |
| `attachments`          | array\<object> | File attachments included in the email.                                                                                |
| `attachments.filename` | string         |                                                                                                                        |
| `params`               | object         | Params passed to the mailer action.                                                                                    |
| `params.*`             | any            | Additional caller-defined keys.                                                                                        |
| `duration`             | number         | Duration in milliseconds.                                                                                              |
| `instrumenter_id`      | string         | Rails instrumenter UUID.                                                                                               |
| `request_id`           | string         | Rails request UUID, present on any event fired during a web request context. Merged globally by the Honeybadger agent. |
| `hostname`             | string         | Server hostname. Attached to every event by default (events.attach\_hostname).                                         |
| `environment`          | string         | Application environment, e.g. "production". Attached to every event by default (events.attach\_environment).           |

## Example

```json
{
  "event_type": "process.action_mailer",
  "mailer": "UserMailer",
  "action": "welcome_email",
  "message_id": "684af2d1c3b4a_1a2b3c4d5e6f@web-1.example.com.mail",
  "subject": "Welcome to Example App",
  "to": [
    "user@example.com"
  ],
  "cc": [
    "support@example.com"
  ],
  "bcc": [
    "audit@example.com"
  ],
  "date": "Fri, 12 Jun 2026 14:30:00 +0000",
  "attachments": [
    {
      "filename": "welcome-guide.pdf"
    }
  ],
  "params": {
    "user_id": 123
  },
  "duration": 84.21,
  "instrumenter_id": "d6a5b3f4c2e1908a7b6c",
  "request_id": "0f5e4bb2-3c46-4b1c-91d5-2f4e8a6b9c01",
  "hostname": "web-1.example.com",
  "environment": "production"
}
```

---

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