Postal Mail Server on Offshore Anubiz Host VPS

Postal is best understood as a self-hosted version of what Mailgun sells. It combines an SMTP server, an HTTP API for application integration, webhook delivery for events like opens, clicks, bounces, and complaints, and a polished admin UI for managing sending servers, organizations, and credentials. The architecture is straightforward: a Ruby on Rails application for the UI and API, a MariaDB or MySQL backend for state, a RabbitMQ or in-process queue for message handling, and a Postfix-style SMTP listener for both submission and outbound delivery. For developers who want a Mailgun-style developer experience but on their own infrastructure, Postal is essentially the only mature open-source option. The project has been actively maintained since 2017 and is in production at multiple ISP-scale operators.

On an Anubiz Host offshore VPS with 4 vCPU and 8GB RAM, install Postal via the official Docker compose deployment. The project publishes a maintained docker-compose configuration that brings up the Rails app, MariaDB, RabbitMQ, and the SMTP listener in coordinated containers. After deployment, configure your sending hostname, set rDNS in the Anubiz Host customer panel to match, then generate API credentials through the Postal admin UI for each application that will submit mail. SPF, DKIM, and DMARC records are managed per sending domain through the UI, which surfaces the exact DNS entries you need to publish. Postal supports both SMTP submission and HTTP API submission. For high-volume bulk sends, the HTTP API with batched requests is the most efficient pattern. For lower-volume transactional traffic, plain SMTP submission with a small connection pool is simpler and works equally well.

Postal's webhook delivery is one of its strongest features. Configure your application to receive HTTPS POST callbacks for events like delivery, bounce, complaint, open, and click. The payload is well-documented JSON, similar in structure to Mailgun events, which makes migration from Mailgun straightforward. Bounce handling is automatic. Postal parses SMTP responses, categorizes bounces as soft or hard, and updates suppression lists per sending server. Your application can query the API for suppression status before sending to a recipient, eliminating the operational headache of manual list hygiene. For long-term operation, snapshot the Postal database and the message storage volume regularly. Anubiz Host hypervisor snapshots cover this cleanly. Application-level backups via mysqldump shipped to offshore object storage provide an additional layer. With these in place, Postal on an Anubiz Host offshore VPS becomes a low-maintenance Mailgun replacement that scales linearly with your mail volume on a flat monthly bill.