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Processing the Email

This section describes the structure and expected content of the email message that is placed in the RabbitMQ queue. When building your own workers, you can use this as a reference to understand the message format and required fields.

note

Note that you need to make sure the email size complies with your RabbitMQ configuration limits.

Email Structure​

The email message placed in the queue is represented by the following structure:

Example of the serialized JSON message
{
    "timestamp": "2025-09-23T23:18:51.477629045+00:00",
    "message_id": "cf4c844f-a317-44f7-97a3-0aaa5be372e3",
    "client_address": "NEKO-NIK-Example",
    "recipients": ["<admin@nekonik.com>"],
    "email_content": "Email body / DATA part",
    "sender": "from-id@nekonik.org"
}

Field Details​

Each field in the email message has specific requirements and constraints. Below are the details for each field:

timestamp​

The timestamp field records the time when the email was created. It follows the RFC3339 format with nanosecond precision.

Example:

2025-09-23T23:18:51.477629045+00:00

message_id​

The message_id field uniquely identifies the email. It is a UUID (version 4) generated at the time of message creation and is used to track the email throughout its processing lifecycle.

Example:

cf4c844f-a317-44f7-97a3-0aaa5be372e3

client_address​

The client_address field indicates the address or identifier of the SMTP client that submitted the email. This value usually corresponds to the identifier provided during the HELO or EHLO phase of the SMTP transaction.

Example:

NEKO-NIK-Example

recipients​

The recipients field contains a list of all email addresses that will receive the message. This includes all direct recipients (TO, CC) as well as any blind carbon copy (BCC) recipients, since these are obtained directly from the SMTP RCPT TO: commands.

Example:

<admin@nekonik.com>

email_content​

The email_content field contains the full body of the email, corresponding to the DATA section in the SMTP protocol. This section includes the complete headers (e.g., Subject, From, To, Date, Content-Type), the message body, and any attachments (encoded as part of a multipart MIME message) as received during the SMTP DATA phase.

Example:

Subject: Welcome to Neko Nik's LSMTP!
From: from-id@nekonik.org
To: admin@nekonik.com
Date: Tue, 23 Sep 2025 23:18:51 +0000
Content-Type: text/plain; charset="UTF-8"

Hello Admin,

This is a test email sent from the Neko Nik mail system.

Regards,
Neko Nik

sender​

The sender field represents the originating email address of the message.

Example:

from-id@nekonik.org

Validation Rules​

The following fields are mandatory for a valid email message:

  • sender
  • recipients
  • email_content
danger

Messages missing any of these fields will be rejected and not accepted into the queue.