WildDuck

WildDuck is an open-source mail server that provides IMAP and POP3 services. It is designed as a scalable system that avoids single points of failure by utilizing a distributed database for the storage of all mail data. The software operates as a server application that manages the retrieval and storage of electronic messages for multiple users.

This system uses a sharded and replicated MongoDB backend to handle email storage, allowing the system to scale across multiple nodes as the volume of data grows. It supports LMTP for receiving mail and provides standard access protocols for email clients to synchronize and download messages. By moving storage away from the local file system, it enables a distributed architecture where multiple server instances can access the same data pool.

Key features

• IMAP server implementation
• POP3 server implementation
• Distributed storage using MongoDB
• Support for sharded database clusters
• Replicated data backend to prevent single points of failure
• LMTP support for mail delivery
• Design patterns based on Gmail's product architecture

WildDuck is part of the Zone Mail Suite, which is a collection of programs and modules intended to create a modern email server environment. The architecture focuses on scalability and high availability by offloading storage to a distributed database rather than relying on traditional Maildir or mbox formats on a local disk. This design allows the server to handle a high volume of concurrent connections and large datasets without the bottlenecks associated with traditional file system locks. It is intended for system administrators and infrastructure engineers who need to deploy a mail storage system that can grow horizontally across a cluster of servers.

It is a backend infrastructure component for organizations requiring a scalable email storage and retrieval system that prioritizes data redundancy and distributed access.