Send Email with Threading

Sends an email using SMTP protocol with reply threading support

Overview

This node sends emails using the SMTP protocol with support for email threading features such as "In-Reply-To" and "References" headers. It is useful in scenarios where automated email sending is required, including notifications, alerts, or follow-up emails that maintain conversation context.

Practical examples:

Sending a notification email to users after a form submission.
Sending marketing emails with attachments.
Replying to an existing email thread programmatically by setting appropriate headers.

Properties

Name	Meaning
From Email	Email address of the sender.
To Email	Email address(es) of the recipient(s). Multiple addresses can be separated by commas.
Subject	Subject line of the email.
Text	Plain text content of the email message.
HTML	HTML content of the email message.
Additional Fields	Collection of optional fields: - Attachments: Array of files with name, base64 content, and MIME type. - BCC Email: Blind copy recipient(s), comma-separated. - CC Email: Copy recipient(s), comma-separated. - In-Reply-To: Message ID this email replies to (for threading). - Priority: Email priority; options are Low, Normal, High. - References: Message IDs in the conversation thread, space or comma separated. - Reply To: Email address for replies.

Output

The node outputs JSON data containing details about the sent email:

messageId: The unique identifier of the sent email message.
accepted: List of recipient addresses accepted by the SMTP server.
rejected: List of recipient addresses rejected by the SMTP server.
response: Raw response from the SMTP server.

Each output item corresponds to one input item processed.

Dependencies

Requires an SMTP server credential configured in n8n to send emails.
Uses an internal utility function to create the SMTP transporter based on provided credentials.
No external API dependencies beyond the SMTP service.

Troubleshooting

Common issues:
- Invalid SMTP credentials or connection failure will cause errors.
- Incorrectly formatted email addresses may lead to rejection by the SMTP server.
- Missing required fields like "From Email" or "To Email" will prevent sending.
- Large or improperly encoded attachments might cause failures.
Error messages:
- Errors from the SMTP server (e.g., authentication failed, connection refused) will be thrown and can be seen in the node's error output.
- If "continue on fail" is enabled, errors for individual items will be returned in the output JSON under an error field.
Resolution tips:
- Verify SMTP credentials and server accessibility.
- Ensure all email addresses are valid and properly formatted.
- Check attachment encoding and size limits.
- Use the "Additional Fields" to set proper threading headers if replying to emails.