Hostwind Infrastructure Management

Automated management of Hostwind VPS instances for scalable email delivery.

Overview

PenguinMails leverages Hostwind for its underlying infrastructure, providing cost-effective, scalable VPS instances for email sending. The platform automates the entire lifecycle of these instances, from provisioning to monitoring and scaling.

Key Capabilities

  • Automated Provisioning - One-click VPS deployment

  • IP Reputation Monitoring - Real-time blacklist checking

  • Resource Scaling - Dynamic CPU/RAM adjustment

  • Health Checks - Automated service recovery

  • Cost Management - Usage tracking and optimization

Level 1: Infrastructure Architecture

The Sending Node

Each “Sending Node” in PenguinMails corresponds to a Hostwind VPS instance configured specifically for email delivery.

Standard Node Configuration:

  • OS: Ubuntu 22.04 LTS

  • MTA: Postfix (custom configuration)

  • IP: Dedicated IPv4 address

  • Reverse DNS: Automatically configured

  • Security: UFW firewall, Fail2Ban

Node Lifecycle 

graph LR
    A[Provisioning] --> B[Warmup]
    B --> C[Active Sending]
    C --> D[Maintenance]
    C --> E[Decommissioned]
    D --> C

  1. Provisioning: API triggers VPS creation, installs dependencies, configures DNS.

  2. Warmup: Node enters “Warmup Mode” with gradually increasing send limits.

  3. Active Sending: Node handles full production traffic.

  4. Maintenance: Temporary removal from rotation for updates or reputation repair.

  5. Decommissioned: Node destroyed, IP released.

Level 2: Automated Management

VPS Provisioning

API-Driven Deployment:

PenguinMails uses the Hostwind API to programmatically create instances.

// POST /api/v1/infrastructure/nodes
{
  "region": "dallas",
  "plan": "ssd-1", // 1 CPU, 1GB RAM
  "label": "node-us-east-045"
}

Provisioning Steps:

  1. Request Instance: Call Hostwind API to create VPS.

  2. Wait for IP: Poll until public IP is assigned.

  3. DNS Setup: Configure A records and rDNS (PTR).

  4. Ansible/Script Setup: SSH into node, install Postfix, Redis, Worker.

  5. Verification: Send test email to internal sink.

  6. Register: Add node to active pool in database.

IP Reputation Monitoring

Continuous Health Checks:

The system continuously monitors the health and reputation of every sending IP.

  • Blacklist Monitoring: Checks against Spamhaus, SORBS, Barracuda, etc.

  • Deliverability Metrics: Tracks bounce rates and complaint rates per IP.

  • Automatic Pausing: If an IP is blacklisted, the node is automatically paused to prevent further damage.

Alerting:

  • Severity High: IP listed on Spamhaus (Immediate pause).

  • Severity Medium: High bounce rate (>5%) detected.

  • Severity Low: High CPU usage on node.

Resource Scaling

Vertical & Horizontal Scaling:

  • Vertical: Upgrade VPS plan (e.g., 1GB → 2GB RAM) via API if queue depth remains high.

  • Horizontal: Provision additional nodes when total system throughput reaches 80% capacity.

Level 3: Technical Implementation

Hostwind API Integration

Authentication: Uses API Key and API Secret stored in secure environment variables.

Key Endpoints Used:

  • POST /instances - Create VPS

  • DELETE /instances/{id} - Destroy VPS

  • GET /instances/{id}/status - Check state

  • POST /instances/{id}/resize - Upgrade plan

Monitoring Agent

Each node runs a lightweight monitoring agent (written in Go or Node.js) that reports back to the central platform.

Metrics Reported:

  • CPU / Memory Usage

  • Disk Space (Mail queue buffer)

  • Postfix Queue Length

  • Network Throughput

Heartbeat Protocol: Nodes send a heartbeat every 30 seconds. If 3 heartbeats are missed, the node is marked “Unhealthy” and removed from the sending rotation.

Database Schema 

CREATE TABLE sending_nodes (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  provider_id VARCHAR(255), -- Hostwind Instance ID
  ip_address INET NOT NULL,
  hostname VARCHAR(255),
  region VARCHAR(50),
  status VARCHAR(50), -- provisioning, active, warming, paused, maintenance
  reputation_score INT DEFAULT 100,
  current_load INT DEFAULT 0,
  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
  last_heartbeat TIMESTAMP
);

CREATE TABLE ip_blacklist_events (
  id UUID PRIMARY KEY,
  node_id UUID REFERENCES sending_nodes(id),
  blacklist_provider VARCHAR(100),
  listed_at TIMESTAMP,
  delisted_at TIMESTAMP,
  details TEXT
);

Infrastructure

Tasks

  • Epic 5: Infrastructure Management - Internal task reference for development tasks

Last Updated: November 24, 2025 Provider: Hostwind Automation: Ansible + Node.js

Automated infrastructure management ensures high availability and consistent deliverability without manual intervention.