Mailcow + n8n Integration: Automated Email Workflows

Why n8n + Mailcow

n8n is an open-source workflow automation platform. Mailcow is a self-hosted email server. Together, they create a fully self-hosted email automation stack that replaces paid services like Mailchimp + Zapier at a fraction of the cost.

n8n handles the logic: triggers, conditions, scheduling, API integrations. Mailcow handles the delivery: SMTP sending, IMAP receiving, authentication, reputation management.

Total infrastructure cost: $10-30/month for both services on a single VPS. Make sure your Mailcow DNS and authentication are configured first.

Sending Email: n8n → Mailcow

Configure SMTP Credentials in n8n

1. In n8n, go to Credentials → Add Credential → SMTP
2. Enter:

Field	Value
Host	mail.yourdomain.com
Port	587
User	[email protected]
Password	(mailbox password)
SSL/TLS	STARTTLS

3. Create the mailbox [email protected] in Mailcow first

Use the Send Email Node

In any n8n workflow, add a Send Email node and select your Mailcow SMTP credentials. Set the From address to match the Mailcow mailbox domain.

Basic send workflow:

Trigger → Process Data → Send Email (via Mailcow SMTP)

The email goes through Mailcow's Postfix, gets DKIM-signed automatically, and delivers with full authentication.

Receiving Email: Mailcow → n8n

IMAP Email Trigger

n8n can poll a Mailcow mailbox for incoming email and trigger workflows:

1. Add an IMAP Email Trigger node
2. Configure credentials:

Field	Value
Host	mail.yourdomain.com
Port	993
User	[email protected]
Password	(mailbox password)
SSL/TLS	Enabled

3. Set the mailbox to INBOX
4. Set poll interval (e.g., every 1 minute)

When an email arrives in that Mailcow mailbox, n8n triggers your workflow with the full email content — subject, body, sender, attachments.

Practitioner note: For inbound email triggers, create a dedicated mailbox like [email protected]. Don't use a personal inbox — n8n will process every incoming message, and you don't want personal email triggering automation workflows.

Practical Automation Recipes

Recipe 1: Welcome Email Sequence

Webhook (new signup) → Wait 0min → Send Welcome Email
                     → Wait 1day → Send Getting Started Email
                     → Wait 3days → Send Tips Email

Each Send Email node uses Mailcow SMTP. The entire sequence runs self-hosted.

Recipe 2: Form Submission → Email Notification

Webhook (form submit) → Format Data → Send Email to Team
                                     → Send Confirmation to Submitter

When someone fills out a form on your site, n8n receives the webhook, formats the data, and sends notification emails through Mailcow.

Recipe 3: Scheduled Digest Email

Cron (daily 8am) → HTTP Request (fetch data) → HTML Template → Send Email

Pull data from your API or database daily, format it as an HTML email, and send through Mailcow. Replace expensive digest/newsletter tools.

Recipe 4: Bounce and Complaint Processing

IMAP Trigger (bounces@domain) → Parse Bounce → Update CRM/Database → Alert if critical

Configure Mailcow to forward bounces to a dedicated mailbox. n8n monitors that mailbox, parses bounce messages, and updates your contact list automatically.

Practitioner note: The bounce processing workflow is the one most people skip and most regret skipping. Automated bounce handling keeps your sender reputation clean without manual list scrubbing. Build this workflow before you start sending volume.

Running Both on One Server

If you want to minimize costs, both n8n and Mailcow run as Docker containers on the same VPS:

Minimum specs: 4GB RAM, 2 vCPU, 40GB SSD

Separate Docker Compose stacks:

/opt/mailcow-dockerized/    → Mailcow stack
/opt/n8n/                    → n8n stack

They share the server but run independently. n8n connects to Mailcow via localhost SMTP (port 587) — no external network latency.

Resource Allocation

Service	RAM Usage	Notes
Mailcow (all containers)	~1.5-2GB	ClamAV is the heaviest
n8n	~200-500MB	Depends on workflow complexity
OS overhead	~300MB
Total	~2.5-3GB	4GB VPS recommended

To reduce Mailcow memory: disable ClamAV if you don't need antivirus scanning (saves ~800MB). Edit mailcow.conf and set SKIP_CLAMD=y.

Separate Servers (Production Recommended)

For production workloads, run them on separate VPSes:

• Mailcow server: $5-10/month (Hetzner CX22/CX32)
• n8n server: $5/month (Hetzner CX22)
• Total: $10-15/month

Benefits: Mailcow updates don't affect n8n, resource contention is eliminated, and you can scale each independently.

Practitioner note: For agencies running both n8n and Mailcow for multiple clients, separate servers is the way. One bad n8n workflow consuming all CPU shouldn't delay email delivery. The extra $5/month for a second VPS is cheap insurance against cross-service resource conflicts.

Monitoring the Integration

Set up these alerts in n8n:

1. Email send failure alert — if the Send Email node fails, trigger a Slack/Discord notification
2. Queue depth monitor — periodically check Mailcow's Postfix queue via API and alert if emails are backing up
3. Bounce rate monitor — track bounce counts and alert if they spike

Mailcow's monitoring dashboard shows queue depth, delivery rates, and error logs. Check it weekly.

If you want a complete self-hosted automation stack set up and integrated, schedule a consultation — I deploy n8n + Mailcow stacks for businesses that want full control over their email automation.

Sources

• n8n: SMTP Node Documentation
• n8n: IMAP Email Trigger
• Mailcow: Docker Configuration
• Mailcow: API Documentation

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v1.0 · April 2026