Cyrus IMAP Installation Guide Installation Guide

Cyrus IMAP is a free and open-source Mail Server. A highly scalable enterprise mail system

Hardware Requirements:

CPU: 2 cores minimum (4+ cores recommended)

RAM: 2GB minimum (4GB+ recommended)

Storage: 1GB for installation

Network: 143/993 ports

Operating System:

Linux: Any modern distribution (RHEL, Debian, Ubuntu, CentOS, Fedora, Arch, Alpine, openSUSE)

macOS: 10.14+ (Mojave or newer)

Windows: Windows Server 2016+ or Windows 10

FreeBSD: 11.0+

Network Requirements:

Port 143/993 (default cyrus-imap port)

Dependencies:

cyrus-sasl, cyrus-admin

System Access: root or sudo privileges required

This guide supports installation on:

RHEL 8/9 and derivatives (CentOS Stream, Rocky Linux, AlmaLinux)

Debian 11/12

Ubuntu 20.04/22.04/24.04 LTS

Arch Linux (rolling release)

Alpine Linux 3.18+

openSUSE Leap 15.5+ / Tumbleweed

SUSE Linux Enterprise Server (SLES) 15+

macOS 12+ (Monterey and later)

FreeBSD 13+

Windows 10/11/Server 2019+ (where applicable)

bash

# Install EPEL repository if needed
sudo dnf install -y epel-release

# Install cyrus-imap
sudo dnf install -y cyrus-imap cyrus-sasl, cyrus-admin

# Enable and start service
sudo systemctl enable --now cyrus-imapd

# Configure firewall
sudo firewall-cmd --permanent --add-service=cyrus-imap
sudo firewall-cmd --reload

# Verify installation
cyrus-imap --version || systemctl status cyrus-imapd

bash

# Update package index
sudo apt update

# Install cyrus-imap
sudo apt install -y cyrus-imap cyrus-sasl, cyrus-admin

# Enable and start service
sudo systemctl enable --now cyrus-imapd

# Configure firewall
sudo ufw allow 143/993

# Verify installation
cyrus-imap --version || systemctl status cyrus-imapd

bash

# Install cyrus-imap
sudo pacman -S cyrus-imap

# Enable and start service
sudo systemctl enable --now cyrus-imapd

# Verify installation
cyrus-imap --version || systemctl status cyrus-imapd

bash

# Install cyrus-imap
apk add --no-cache cyrus-imap

# Enable and start service
rc-update add cyrus-imapd default
rc-service cyrus-imapd start

# Verify installation
cyrus-imap --version || rc-service cyrus-imapd status

bash

# Install cyrus-imap
sudo zypper install -y cyrus-imap cyrus-sasl, cyrus-admin

# Enable and start service
sudo systemctl enable --now cyrus-imapd

# Configure firewall
sudo firewall-cmd --permanent --add-service=cyrus-imap
sudo firewall-cmd --reload

# Verify installation
cyrus-imap --version || systemctl status cyrus-imapd

bash

# Using Homebrew
brew install cyrus-imap

# Start service
brew services start cyrus-imap

# Verify installation
cyrus-imap --version

bash

# Using pkg
pkg install cyrus-imap

# Enable in rc.conf
echo 'cyrus-imapd_enable="YES"' >> /etc/rc.conf

# Start service
service cyrus-imapd start

# Verify installation
cyrus-imap --version || service cyrus-imapd status

powershell

# Using Chocolatey
choco install cyrus-imap

# Or using Scoop
scoop install cyrus-imap

# Verify installation
cyrus-imap --version

bash

# Create configuration directory if needed
sudo mkdir -p /etc/cyrus-imapd

# Set up basic configuration
sudo tee /etc/cyrus-imapd/cyrus-imap.conf << 'EOF'
# Cyrus IMAP Configuration
maxchild: 100, maxconnections: 1000
EOF

# Test configuration
sudo cyrus-imap -t || sudo cyrus-imapd configtest

# Reload service
sudo systemctl reload cyrus-imapd

bash

# Set appropriate permissions
sudo chown -R cyrus-imap:cyrus-imap /etc/cyrus-imapd
sudo chmod 750 /etc/cyrus-imapd

# Enable security features
# See security section for detailed hardening steps

bash

# Enable service
sudo systemctl enable cyrus-imapd

# Start service
sudo systemctl start cyrus-imapd

# Stop service
sudo systemctl stop cyrus-imapd

# Restart service
sudo systemctl restart cyrus-imapd

# Reload configuration
sudo systemctl reload cyrus-imapd

# Check status
sudo systemctl status cyrus-imapd

# View logs
sudo journalctl -u cyrus-imapd -f

bash

# Enable service
rc-update add cyrus-imapd default

# Start service
rc-service cyrus-imapd start

# Stop service
rc-service cyrus-imapd stop

# Restart service
rc-service cyrus-imapd restart

# Check status
rc-service cyrus-imapd status

bash

# Enable in /etc/rc.conf
echo 'cyrus-imapd_enable="YES"' >> /etc/rc.conf

# Start service
service cyrus-imapd start

# Stop service
service cyrus-imapd stop

# Restart service
service cyrus-imapd restart

# Check status
service cyrus-imapd status

bash

# Using Homebrew services
brew services start cyrus-imap
brew services stop cyrus-imap
brew services restart cyrus-imap

# Check status
brew services list | grep cyrus-imap

powershell

# Start service
net start cyrus-imapd

# Stop service
net stop cyrus-imapd

# Using PowerShell
Start-Service cyrus-imapd
Stop-Service cyrus-imapd
Restart-Service cyrus-imapd

# Check status
Get-Service cyrus-imapd

bash

# Configure performance settings
cat >> /etc/cyrus-imapd/cyrus-imap.conf << 'EOF'
maxchild: 100, maxconnections: 1000
EOF

# Apply system tuning
sudo sysctl -w net.core.somaxconn=65535
sudo sysctl -w net.ipv4.tcp_max_syn_backlog=65535

# Restart service
sudo systemctl restart cyrus-imapd

bash

# Configure clustering (if supported)
# See official documentation for cluster setup

# Basic load balancing setup example
# Configure multiple instances on different ports

nginx

upstream cyrus-imap_backend {
    server 127.0.0.1:143/993;
    server 127.0.0.1:{default_port}1 backup;
}

server {
    listen 80;
    server_name cyrus-imap.example.com;
    return 301 https://$server_name$request_uri;
}

server {
    listen 443 ssl http2;
    server_name cyrus-imap.example.com;

    ssl_certificate /etc/ssl/certs/cyrus-imap.example.com.crt;
    ssl_certificate_key /etc/ssl/private/cyrus-imap.example.com.key;

    location / {
        proxy_pass http://cyrus-imap_backend;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        
        # WebSocket support (if needed)
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
    }
}

apache

<VirtualHost *:80>
    ServerName cyrus-imap.example.com
    Redirect permanent / https://cyrus-imap.example.com/
</VirtualHost>

<VirtualHost *:443>
    ServerName cyrus-imap.example.com
    
    SSLEngine on
    SSLCertificateFile /etc/ssl/certs/cyrus-imap.example.com.crt
    SSLCertificateKeyFile /etc/ssl/private/cyrus-imap.example.com.key
    
    ProxyRequests Off
    ProxyPreserveHost On
    
    ProxyPass / http://127.0.0.1:143/993/
    ProxyPassReverse / http://127.0.0.1:143/993/
    
    # WebSocket support (if needed)
    RewriteEngine on
    RewriteCond %{HTTP:Upgrade} websocket [NC]
    RewriteCond %{HTTP:Connection} upgrade [NC]
    RewriteRule ^/?(.*) "ws://127.0.0.1:143/993/$1" [P,L]
</VirtualHost>

haproxy

frontend cyrus-imap_frontend
    bind *:80
    bind *:443 ssl crt /etc/ssl/certs/cyrus-imap.pem
    redirect scheme https if !{ ssl_fc }
    default_backend cyrus-imap_backend

backend cyrus-imap_backend
    balance roundrobin
    option httpchk GET /health
    server cyrus-imap1 127.0.0.1:143/993 check
    server cyrus-imap2 127.0.0.1:{default_port}1 check backup

bash

# Set appropriate permissions
sudo chown -R cyrus-imap:cyrus-imap /etc/cyrus-imapd
sudo chmod 750 /etc/cyrus-imapd

# Configure firewall
sudo firewall-cmd --permanent --add-service=cyrus-imap
sudo firewall-cmd --reload

# Enable SELinux policies (if applicable)
sudo setsebool -P httpd_can_network_connect on

# Configure fail2ban
sudo tee /etc/fail2ban/jail.d/cyrus-imap.conf << 'EOF'
[cyrus-imap]
enabled = true
port = 143/993
filter = cyrus-imap
logpath = /var/log/cyrus/*.log
maxretry = 5
bantime = 3600
EOF

bash

# Generate SSL certificates
sudo openssl req -x509 -nodes -days 365 -newkey rsa:2048 \
    -keyout /etc/ssl/private/cyrus-imap.key \
    -out /etc/ssl/certs/cyrus-imap.crt

# Configure SSL in cyrus-imap
# See official documentation for SSL configuration

PostgreSQL Backend (if applicable)

bash

# Create database and user
sudo -u postgres psql << EOF
CREATE DATABASE cyrus-imap_db;
CREATE USER cyrus-imap_user WITH ENCRYPTED PASSWORD 'secure_password';
GRANT ALL PRIVILEGES ON DATABASE cyrus-imap_db TO cyrus-imap_user;
EOF

# Configure cyrus-imap to use PostgreSQL
# See official documentation for database configuration

bash

# Create database and user
sudo mysql << EOF
CREATE DATABASE cyrus-imap_db;
CREATE USER 'cyrus-imap_user'@'localhost' IDENTIFIED BY 'secure_password';
GRANT ALL PRIVILEGES ON cyrus-imap_db.* TO 'cyrus-imap_user'@'localhost';
FLUSH PRIVILEGES;
EOF

bash

# Kernel parameters
sudo tee -a /etc/sysctl.conf << EOF
net.core.somaxconn = 65535
net.ipv4.tcp_max_syn_backlog = 65535
net.ipv4.ip_local_port_range = 1024 65535
net.core.netdev_max_backlog = 5000
vm.swappiness = 10
EOF

sudo sysctl -p

# Cyrus IMAP specific tuning
maxchild: 100, maxconnections: 1000

bash

# Configure system limits
sudo tee -a /etc/security/limits.conf << EOF
cyrus-imap soft nofile 65535
cyrus-imap hard nofile 65535
cyrus-imap soft nproc 32768
cyrus-imap hard nproc 32768
EOF

yaml

# prometheus.yml configuration
scrape_configs:
  - job_name: 'cyrus-imap'
    static_configs:
      - targets: ['localhost:143/993']
    metrics_path: '/metrics'

bash

# Basic health check script
#!/bin/bash
if systemctl is-active --quiet cyrus-imapd; then
    echo "Cyrus IMAP is running"
    exit 0
else
    echo "Cyrus IMAP is not running"
    exit 1
fi

bash

# Configure log rotation
sudo tee /etc/logrotate.d/cyrus-imap << 'EOF'
/var/log/cyrus/*.log {
    daily
    rotate 14
    compress
    delaycompress
    missingok
    notifempty
    create 0640 cyrus-imap cyrus-imap
    postrotate
        systemctl reload cyrus-imapd > /dev/null 2>&1 || true
    endscript
}
EOF

bash

#!/bin/bash
# Cyrus IMAP backup script
BACKUP_DIR="/backup/cyrus-imap"
DATE=$(date +%Y%m%d_%H%M%S)

mkdir -p "$BACKUP_DIR"

# Stop service (if required)
systemctl stop cyrus-imapd

# Backup configuration
tar -czf "$BACKUP_DIR/cyrus-imap-config-$DATE.tar.gz" /etc/cyrus-imapd

# Backup data (adjust paths as needed)
tar -czf "$BACKUP_DIR/cyrus-imap-data-$DATE.tar.gz" /var/lib/cyrus-imap

# Start service
systemctl start cyrus-imapd

# Clean old backups (keep 30 days)
find "$BACKUP_DIR" -name "*.tar.gz" -mtime +30 -delete

echo "Backup completed: $BACKUP_DIR"

bash

# Stop service
sudo systemctl stop cyrus-imapd

# Restore configuration
sudo tar -xzf /backup/cyrus-imap/cyrus-imap-config-*.tar.gz -C /

# Restore data
sudo tar -xzf /backup/cyrus-imap/cyrus-imap-data-*.tar.gz -C /

# Set permissions
sudo chown -R cyrus-imap:cyrus-imap /etc/cyrus-imapd
sudo chown -R cyrus-imap:cyrus-imap /var/lib/cyrus-imap

# Start service
sudo systemctl start cyrus-imapd

1. Service won't start:

bash

# Check logs
sudo journalctl -u cyrus-imapd -n 100
sudo tail -f /var/log/cyrus/*.log

# Check configuration
sudo cyrus-imap -t || sudo cyrus-imapd configtest

# Check permissions
ls -la /etc/cyrus-imapd
ls -la /var/lib/cyrus-imap

2. Connection refused:

bash

# Check if service is listening
sudo ss -tlnp | grep 143/993
sudo netstat -tlnp | grep 143/993

# Check firewall
sudo firewall-cmd --list-all
sudo iptables -L -n

# Test connection
telnet localhost 143/993
nc -zv localhost 143/993

3. Performance issues:

bash

# Check resource usage
top -p $(pgrep imapd)
htop -p $(pgrep imapd)

# Check connections
ss -ant | grep :143/993 | wc -l

# Monitor I/O
iotop -p $(pgrep imapd)

bash

# Run in debug mode
sudo cyrus-imap -d
# or
sudo cyrus-imapd debug

# Increase log verbosity
# Edit configuration to enable debug logging

yaml

version: '3.8'
services:
  cyrus-imap:
    image: cyrus-imap:latest
    container_name: cyrus-imap
    ports:
      - "143/993:143/993"
    volumes:
      - ./config:/etc/cyrus-imapd
      - ./data:/var/lib/cyrus-imap
    environment:
      - cyrus-imap_CONFIG=/etc/cyrus-imapd/cyrus-imap.conf
    restart: unless-stopped
    networks:
      - cyrus-imap_net

networks:
  cyrus-imap_net:
    driver: bridge

yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: cyrus-imap
spec:
  replicas: 3
  selector:
    matchLabels:
      app: cyrus-imap
  template:
    metadata:
      labels:
        app: cyrus-imap
    spec:
      containers:
      - name: cyrus-imap
        image: cyrus-imap:latest
        ports:
        - containerPort: 143/993
        volumeMounts:
        - name: config
          mountPath: /etc/cyrus-imapd
      volumes:
      - name: config
        configMap:
          name: cyrus-imap-config
---
apiVersion: v1
kind: Service
metadata:
  name: cyrus-imap
spec:
  selector:
    app: cyrus-imap
  ports:
  - port: 143/993
    targetPort: 143/993
  type: LoadBalancer

yaml

---
- name: Install and configure Cyrus IMAP
  hosts: all
  become: yes
  tasks:
    - name: Install cyrus-imap
      package:
        name: cyrus-imap
        state: present
    
    - name: Configure cyrus-imap
      template:
        src: cyrus-imap.conf.j2
        dest: /etc/cyrus-imapd/cyrus-imap.conf
        owner: cyrus-imap
        group: cyrus-imap
        mode: '0640'
      notify: restart cyrus-imap
    
    - name: Start and enable cyrus-imap
      systemd:
        name: cyrus-imapd
        state: started
        enabled: yes
  
  handlers:
    - name: restart cyrus-imap
      systemd:
        name: cyrus-imapd
        state: restarted

Maintenance

bash

# RHEL/CentOS/Rocky/AlmaLinux
sudo dnf update cyrus-imap

# Debian/Ubuntu
sudo apt update && sudo apt upgrade cyrus-imap

# Arch Linux
sudo pacman -Syu cyrus-imap

# Alpine Linux
apk update && apk upgrade cyrus-imap

# openSUSE
sudo zypper update cyrus-imap

# FreeBSD
pkg update && pkg upgrade cyrus-imap

# Always backup before updates
tar -czf /backup/cyrus-imap-pre-update-$(date +%Y%m%d).tar.gz /etc/cyrus-imapd

# Restart after updates
sudo systemctl restart cyrus-imapd

Regular Maintenance Tasks

bash

# Clean logs
find /var/log/cyrus -name "*.log" -mtime +30 -delete

# Verify integrity
sudo cyrus-imap --verify || sudo cyrus-imapd check

# Update databases (if applicable)
sudo cyrus-imap-update-db

# Optimize performance
sudo cyrus-imap-optimize

# Check for security updates
sudo cyrus-imap --security-check

Official Documentation: https://docs.cyrus-imap.org/

GitHub Repository: https://github.com/cyrus-imap/cyrus-imap

Community Forum: https://forum.cyrus-imap.org/

Wiki: https://wiki.cyrus-imap.org/

Comparison vs Dovecot, Courier, Zimbra, Exchange: https://docs.cyrus-imap.org/comparison

---

Note: This guide is part of the HowToMgr collection. Always refer to official documentation for the most up-to-date information.

1. Prerequisites

2. Supported Operating Systems

3. Installation

RHEL/CentOS/Rocky Linux/AlmaLinux

Debian/Ubuntu

Arch Linux

Alpine Linux

openSUSE/SLES

macOS

FreeBSD

Windows

Initial Configuration

Basic Configuration

Security Hardening

5. Service Management

systemd (RHEL, Debian, Ubuntu, Arch, openSUSE)

OpenRC (Alpine Linux)

rc.d (FreeBSD)

launchd (macOS)

Windows Service Manager

Advanced Configuration

Performance Optimization

Clustering and High Availability

Reverse Proxy Setup

nginx Configuration

Apache Configuration

HAProxy Configuration

Security Configuration

Basic Security Setup

SSL/TLS Configuration

Database Setup

PostgreSQL Backend (if applicable)

MySQL/MariaDB Backend (if applicable)

Performance Optimization

System Tuning

Resource Limits

Monitoring

Prometheus Integration

Health Checks

Log Monitoring

9. Backup and Restore

Backup Script

Restore Procedure

6. Troubleshooting

Common Issues

Debug Mode

Integration Examples

Docker Compose

Kubernetes Deployment

Ansible Playbook

Maintenance

Update Procedures

Regular Maintenance Tasks

Additional Resources

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