Supabase + Gmail Bulk Email n8n Workflow: Webhook & Schedule

Send bulk emails with Gmail—instantly via webhook or automatically every day from Supabase

This n8n workflow lets you send Gmail emails either on-demand through a POST webhook or on a daily schedule by reading email drafts from Supabase. It’s built for SaaS operators and automation engineers who need reliable, repeatable bulk email delivery with clear JSON responses.

What this workflow does

• Webhook (on-demand) delivery: Receives a POST request containing subject, message, and a recipients list.
• One email per recipient: Splits the incoming payload into one item per recipient address so each email can be sent individually.
• Gmail sending + confirmation: Uses the Gmail node to send each message and returns a JSON response confirming the email was sent.
• Daily scheduled delivery (Supabase-driven): Runs on a daily schedule and fetches rows from a Supabase table containing subject, message, and recipients.
• Single email with all recipients: Joins recipients into one list, builds the combined email, and sends it through Gmail.

Use cases

• Send targeted announcements immediately after a user action triggers a webhook.
• Run daily outbound email batches stored in Supabase (e.g., follow-ups, notifications, scheduled campaigns).
• Centralize email content and recipient lists in Supabase, while keeping delivery logic in n8n.

Technical details

• Webhook node: provides a daily-email endpoint for POST requests.
• Schedule Trigger: runs the daily job.
• Supabase integration: reads from a configured table (example: messages with subject/message/recipients).
• Gmail integration: uses an OAuth2 credential with permission to send email.
• Code node: handles splitting the webhook payload into one item per recipient.
• Sticky note: included for workflow guidance.

Setup tip: Add your Gmail OAuth2 credential, add your Supabase API credential and table name, then copy the webhook URL for the daily-email endpoint and POST subject, message, and recipients to it.