IMAP Downloader

A simple Python script to download all emails from an IMAP server into individual EML files, preserving the folder structure.

Features

• Downloads emails as standard .eml files
• Preserves IMAP folder hierarchy locally
• Extracts attachments into zip files alongside each email
• Supports SSL and STARTTLS connections
• Incremental updates using UID tracking (only download new emails)
• Multi-account support (separate folders per email address)
• Configurable download limit for testing/debugging

Requirements

• Python 3.6+
• No external dependencies (uses only standard library)

Installation

# Clone or download the script
git clone <repo-url>
cd imapdown

# Create virtual environment (optional but recommended)
python3 -m venv .venv
source .venv/bin/activate

Usage

Basic Usage

By default, the script only downloads new emails since the last run (incremental mode). On first run, it downloads everything.

# Download emails using SSL (most common)
./imapdown.py --server imap.example.com --email me@example.com --user me@example.com --password "secret" --ssl

# Using STARTTLS
./imapdown.py --server imap.example.com --email me@example.com --user me@example.com --password "secret" --starttls

# Custom port
./imapdown.py --server imap.example.com --email me@example.com --user me@example.com --password "secret" --ssl --port 12993

# Custom storage directory
./imapdown.py --server imap.example.com --email me@example.com --user me@example.com --password "secret" --ssl --store /path/to/backup

Full Download

To force a complete download of all emails (ignoring previous state):

./imapdown.py --server imap.example.com --email me@example.com --user me@example.com --password "secret" --ssl --full

Note: As a safety measure, --full will refuse to run if the download folder already contains emails. This prevents accidental duplicates. To re-download everything, first delete the folder:

rm -rf download/me@example.com/
./imapdown.py --server imap.example.com --email me@example.com --user me@example.com --password "secret" --ssl --full

Debugging/Testing

Limit the number of emails downloaded:

./imapdown.py --server imap.example.com --email me@example.com --user me@example.com --password "secret" --ssl --limit 10

Command Line Arguments

Argument	Required	Description
--server	Yes	IMAP server hostname
--email	Yes	Email address (used for folder organization)
--user	Yes	Username for authentication
--password	Yes	Password for authentication
--ssl	No	Use implicit SSL/TLS (default port 993)
--starttls	No	Use STARTTLS (default port 143)
--port	No	Custom port (overrides defaults)
--limit	No	Maximum number of emails to download
--full	No	Download all emails (default: only new since last run)
--store	No	Directory to store downloaded emails (default: ./download)

Note: --ssl and --starttls are mutually exclusive.

Output Structure

The default output structure (when --store is not specified):

./download/
├── user@example.com/
│   ├── .imapdown_state.json      # Tracks last downloaded UID per folder
│   ├── INBOX/
│   │   ├── 123_20240115_Meeting_notes.eml
│   │   ├── 124_20240116_Report.eml
│   │   └── 124_20240116_Report.zip    # Attachments (if any)
│   ├── Sent/
│   │   └── 456_20240114_RE_Question.eml
│   └── Archive/
│       └── 789_20240101_Old_email.eml
└── another@example.com/
    └── ...

File Naming

Email files are named: {UID}_{date}_{subject}.eml

• UID: Unique identifier from the IMAP server
• date: Message date in YYYYMMDD_HHMMSS format
• subject: Sanitized email subject (truncated to 50 characters)

Attachments

When an email contains attachments, they are extracted and saved in a zip file with the same base name as the .eml file but with a .zip extension.

State Tracking

The script maintains a .imapdown_state.json file in each email account's folder. This file tracks the highest downloaded UID for each IMAP folder, enabling efficient incremental updates with --update.

Example state file:

{
  "INBOX": 19334,
  "INBOX.Archive": 1770,
  "Sent": 892
}

License

MIT