How to Self-Host Your Own Email Server with Mailcow

Running your own email server is one of the most challenging self-hosting projects. But with Mailcow, it’s actually manageable.

This guide shows you how to set up a complete, production-ready email server with Mailcow—handling everything from DNS to spam filtering to webmail.

Why Self-Host Email?

Pros:

Complete control over your data
Custom domain email ([email protected])
No storage limits
No scanning of your emails
Learning experience

Cons:

Complex setup
Requires dedicated server with static IP
Deliverability challenges (avoiding spam folders)
Ongoing maintenance required

Reality Check: Self-hosting email is hard. Gmail and Proton Mail exist for good reasons. Only do this if you understand the commitment.

Prerequisites

Required:

Dedicated server with static public IP (no dynamic IPs, no residential ISP)
Domain name with full DNS control
2GB+ RAM minimum (4GB recommended)
20GB+ storage
Port 25 NOT blocked by ISP (most cloud providers block this—check first!)

Providers that allow port 25:

Hetzner (Germany)
OVH
Vultr (some regions)
DigitalOcean (request unblock)

Providers that DON’T allow port 25:

AWS EC2 (requires forms/justification)
Google Cloud
Azure
Most residential ISPs

Architecture Overview

Mailcow includes:

Postfix - SMTP server (sending/receiving)
Dovecot - IMAP/POP3 (email storage)
Rspamd - Spam filtering
SOGo - Webmail interface
ClamAV - Antivirus
Redis, MySQL - Databases
Nginx - Web server

All run in Docker containers, managed together.

Step 1: Server Setup

# Update system
apt update && apt upgrade -y

# Install Docker
curl -fsSL https://get.docker.com | sh

# Install Docker Compose
apt install docker-compose-plugin -y

# Create mailcow user (optional but recommended)
useradd -m -s /bin/bash mailcow
usermod -aG docker mailcow
su - mailcow

Step 2: DNS Configuration

Critical: Get DNS right FIRST. Email won’t work otherwise.

Required DNS Records

Replace mail.yourdomain.com with your mail server hostname.

DKIM will be generated after Mailcow installation.

Verify DNS

# Check MX record
dig +short MX yourdomain.com

# Check A record
dig +short mail.yourdomain.com

# Check SPF
dig +short TXT yourdomain.com

Step 3: Install Mailcow

cd /opt
git clone https://github.com/mailcow/mailcow-dockerized
cd mailcow-dockerized

# Generate configuration
./generate_config.sh

You’ll be asked:

Mail server hostname: mail.yourdomain.com
Timezone: America/New_York (or your timezone)

Step 4: Configure Mailcow

Edit mailcow.conf:

nano mailcow.conf

Important settings:

# Hostname (FQDN)
MAILCOW_HOSTNAME=mail.yourdomain.com

# Timezone
TZ=America/New_York

# HTTP/HTTPS ports (change if needed)
HTTP_PORT=80
HTTPS_PORT=443

# Let's Encrypt (enable for SSL)
SKIP_LETS_ENCRYPT=n

# Admin password (change this!)
# Leave blank to auto-generate

Step 5: Start Mailcow

docker compose pull
docker compose up -d

Wait 5-10 minutes for all containers to start and initialize.

Check status:

docker compose ps

All services should be “Up” and healthy.

Step 6: Initial Setup

Access web admin: https://mail.yourdomain.com

Default credentials:

Username: admin
Password: moohoo

CHANGE THE PASSWORD IMMEDIATELY

Step 7: Add DKIM Record

Go to Configuration → Configuration & Details → ARC/DKIM keys
Click on your domain
Copy the DKIM public key
Add to DNS:

Verify:

dig +short TXT dkim._domainkey.yourdomain.com

Step 8: Create Mailbox

Go to Mailboxes → Add mailbox
Local part: you
Domain: yourdomain.com
Full email: [email protected]
Set password
Click Add

Step 9: Test Email Sending

Use webmail at https://mail.yourdomain.com/SOGo

Send a test email to Gmail or another service.

Check spam score:

Send to: [email protected]
You’ll receive a detailed report

Step 10: Configure Email Client

Use these settings in Thunderbird, Outlook, or mobile:

IMAP (Receiving):

Server: mail.yourdomain.com
Port: 993
Security: SSL/TLS
Username: [email protected]
Password: (your mailbox password)

SMTP (Sending):

Server: mail.yourdomain.com
Port: 587
Security: STARTTLS
Username: [email protected]
Password: (your mailbox password)

Spam Filtering Configuration

Mailcow uses Rspamd for spam filtering.

Adjust spam threshold:

Go to System → Configuration → Rspamd
Default threshold: 15 (lower = stricter)
Recommended: 7-10 for personal use

Greylisting:

Enabled by default
Delays first-time senders by 5 minutes
Reduces spam significantly

Security Hardening

Enable Two-Factor Authentication

Go to Access → Two-Factor Authentication
Scan QR code with authenticator app
Enable 2FA

Restrict Admin Access

# Edit mailcow.conf
nano mailcow.conf

# Add allowed IPs
ADMIN_IP_RANGE=192.168.1.0/24,your.public.ip

Restart:

docker compose down && docker compose up -d

Enable Fail2Ban

Mailcow has built-in fail2ban:

# Check status
docker compose exec fail2ban-mailcow fail2ban-client status

Bans IPs after failed login attempts.

Backup Strategy

Automated Backup

Mailcow includes backup script:

cd /opt/mailcow-dockerized
./helper-scripts/backup_and_restore.sh backup all

Schedule daily backups:

crontab -e

# Add:
0 2 * * * cd /opt/mailcow-dockerized && ./helper-scripts/backup_and_restore.sh backup all

What Gets Backed Up

Mail data (all emails)
MySQL databases
Redis data
Rspamd configuration
SSL certificates

Restore from Backup

./helper-scripts/backup_and_restore.sh restore

Monitoring & Maintenance

Check Mail Queue

docker compose exec postfix-mailcow mailq

Empty queue = good. Stuck emails = investigate logs.

View Logs

# All containers
docker compose logs -f

# Specific service
docker compose logs -f postfix-mailcow
docker compose logs -f dovecot-mailcow

Update Mailcow

cd /opt/mailcow-dockerized
./update.sh

Run monthly or when security updates are announced.

Deliverability Tips

Warm Up Your IP

Don’t send 1000 emails on day one. Gradually increase volume:

Week 1: 10-20 emails/day
Week 2: 50-100 emails/day
Week 3: 200+ emails/day

Monitor Reputation

Check your IP and domain reputation:

Avoid Blacklists

Don’t send spam (obvious but critical)
Set up DKIM, SPF, DMARC correctly
Monitor for compromised accounts
Enable rate limiting

Troubleshooting

Emails Going to Spam

Check:

DNS records (SPF, DKIM, DMARC)
Reverse DNS (PTR record)
IP reputation (check blacklists)
Email content (avoid spam trigger words)

Cannot Send Email

Check:

Port 25 not blocked by ISP
Firewall allows ports 25, 587, 993
SMTP logs: docker compose logs postfix-mailcow

Cannot Receive Email

Check:

MX record points to correct server
Port 25 open on firewall
Postfix logs: docker compose logs postfix-mailcow

Common Issues

“Connection Refused” on Port 25

Your ISP blocks port 25. Switch to a provider that doesn’t.

Emails from Gmail Going to Spam

Gmail is strict. Ensure:

PTR record matches hostname
DKIM signature valid
SPF passes
Gradually build reputation

High CPU Usage

ClamAV virus scanning uses CPU. Disable if not needed:

nano docker-compose.override.yml

# Add:
services:
  clamd-mailcow:
    entrypoint: ["echo", "Service disabled"]

Advanced Features

Aliases & Forwarding

Create email aliases (e.g., support@ → your main inbox):

Mailboxes → Add alias
Forward to existing mailbox

Catch-All Address

Receive all emails to undefined addresses:

Mailboxes → yourdomain.com → Edit
Enable catch-all

Sieve Filters

Create server-side email rules:

Mailboxes → Your mailbox → Sieve filters
Add rules (move to folder, mark as read, etc.)

Alternatives to Mailcow

Mail-in-a-Box - Simpler but less features
iRedMail - Older, still maintained
Mailu - Lighter weight
Docker Mailserver - More manual configuration

Why Mailcow? Best balance of features, ease of use, and active development.

Conclusion

Self-hosting email with Mailcow is achievable if you:

Have a proper server (static IP, port 25 allowed)
Configure DNS correctly
Follow security best practices
Commit to ongoing maintenance

It’s not for everyone, but if you want full control over your email, Mailcow is the way.

Next Steps

Set up backups (daily automation)
Enable 2FA for all accounts
Monitor blacklists weekly
Configure advanced spam filtering
Set up external backup destination

Running Mailcow? Share your experience in the comments!

Why Self-Host Email?#

Prerequisites#

Architecture Overview#

Step 1: Server Setup#

Step 2: DNS Configuration#

Required DNS Records#

Verify DNS#

Step 3: Install Mailcow#

Step 4: Configure Mailcow#

Step 5: Start Mailcow#

Step 6: Initial Setup#

Step 7: Add DKIM Record#

Step 8: Create Mailbox#

Step 9: Test Email Sending#

Step 10: Configure Email Client#

Spam Filtering Configuration#

Security Hardening#

Enable Two-Factor Authentication#

Restrict Admin Access#

Enable Fail2Ban#

Backup Strategy#

Automated Backup#

What Gets Backed Up#

Restore from Backup#

Monitoring & Maintenance#

Check Mail Queue#

View Logs#

Update Mailcow#

Deliverability Tips#

Warm Up Your IP#

Monitor Reputation#

Avoid Blacklists#

Troubleshooting#

Emails Going to Spam#

Cannot Send Email#

Cannot Receive Email#

Common Issues#

“Connection Refused” on Port 25#

Emails from Gmail Going to Spam#

High CPU Usage#

Advanced Features#

Aliases & Forwarding#

Catch-All Address#

Sieve Filters#

Alternatives to Mailcow#

Conclusion#

Next Steps#

📬 Get Self-Hosting Tips in Your Inbox

Why Self-Host Email?

Prerequisites

Architecture Overview

Step 1: Server Setup

Step 2: DNS Configuration

Required DNS Records

Verify DNS

Step 3: Install Mailcow

Step 4: Configure Mailcow

Step 5: Start Mailcow

Step 6: Initial Setup

Step 7: Add DKIM Record

Step 8: Create Mailbox

Step 9: Test Email Sending

Step 10: Configure Email Client

Spam Filtering Configuration

Security Hardening

Enable Two-Factor Authentication

Restrict Admin Access

Enable Fail2Ban

Backup Strategy

Automated Backup

What Gets Backed Up

Restore from Backup

Monitoring & Maintenance

Check Mail Queue

View Logs

Update Mailcow

Deliverability Tips

Warm Up Your IP

Monitor Reputation

Avoid Blacklists

Troubleshooting

Emails Going to Spam

Cannot Send Email

Cannot Receive Email

Common Issues

“Connection Refused” on Port 25

Emails from Gmail Going to Spam

High CPU Usage

Advanced Features

Aliases & Forwarding

Catch-All Address

Sieve Filters

Alternatives to Mailcow

Conclusion

Next Steps