What is Maildir & Maildir ++ File: A Brief Introduction
It is an email format which is used for storing messages only. It is a more organized and systematic way of storing mailbox data. It was introduced by Qmail client and is used by many other applications like Mozilla Thunderbird. It creates a separate file with a unique name for each incoming message.
One Such Extension to Maildir was found, named as Maildir++ which aimed at supporting mail quotas & sub-folders. The Sub-directories within Maildir++ files start with (dot) "." (eg, " .Inbox ", ".Drafts " etc.). This Maildir++ files follows the same specification as that of Maildir
Key Differences Between Maildir and Maildir++ Files
The below listed table provides a concise overview of the key differences between Maildir and Maildir++ files. Highlighting their respective features and suitability for different use cases.
| Features | Maildir | Maildir++ |
|---|---|---|
| Subfolder Support | Does not support subfolders. | Supports subfolders, allowing for hierarchical folder structures. |
| Quota Management | Does not include built-in quota management features. | Includes quota management capabilities for controlling storage usage. |
| Scalability | Highly scalable for basic email storage needs. | Suitable for larger organizations or service providers with extensive storage requirements. |
| Compatibility | Widely compatible with email clients and systems. | Maintains backward compatibility with Maildir while offering additional features. |
| Maintenance | Relatively simple to maintain and manage. | Requires additional configuration and management for quota and subfolder support. |
| Usage | Suitable for basic email storage and retrieval. | Ideal for environments requiring detailed folder structures and quota management. |
Quick Glance at Maildir File Structure
After Knowing about What is Maildir. Lets know about Maildir Directory Structure. This file type organises each folder in a new directory. The most important ones are discussed below:
- Tmp: It stores the emails temporarily for the current mailbox.
- New: Each incoming message is saved in this sub-directory (which is unread). It saves the meta properties of emails including ‘Return-path’ and ‘Delivered-To’ details. This information can be crucial in forensic analysis and for tracing the route or path taken by the email. The Maildir file extension receives messages in RFC 822 format. It keeps the text integrity intact. This directory also keeps a record of creation date and any last modifications or edits made.
- Cur: It saves all the messages that have already been read. This indicates the very organized structure of the Maildir file format. It creates a separate folder for keeping the opened messages. It helps investigators to examine a cybercrime by scanning only part of the database.
The above image displays a pictorial representation of how a typical client stores data using Maildir file format. The structure defines a home directory that branches into a separate folder for each user. One can browse to different sub-directories created for each account to read emails corresponding to that particular mailbox.
