proton-to-icloud

Migrate Proton Mail exports (.eml files) to iCloud Mail via IMAP.

Why?

Proton Mail lets you export your mailbox as .eml files, but Apple Mail has no reliable bulk-import for thousands of .eml files. Drag-and-drop silently drops messages, File > Import creates a folder per file, and .mbox renaming is rejected outright.

proton-to-icloud solves this by uploading .eml files directly to iCloud via IMAP APPEND, preserving original dates, read/unread status, and folder structure. It's a zero-dependency Python CLI tool that you can install globally with pipx or uv tool install.

Features

• Direct IMAP upload — bypasses Apple Mail entirely, talks to imap.mail.me.com over SSL
• Preserves original dates — parses the Date: header from each .eml and sets the IMAP internal date accordingly
• Automatic resume — saves progress to a state file every 100 messages; resumes where you left off after interruptions
• Progress bar — live terminal progress with ETA, throughput, and success/failure counts
• Batch splitting — optionally split thousands of .eml files into numbered batch folders
• Zero dependencies — stdlib only, no conflicts when installed globally
• Folder routing — automatically routes emails to the correct IMAP folders (Inbox, Sent, Archive, etc.) based on Proton metadata
• Dry-run mode — scan and count files without connecting or uploading

Installation

With uv (recommended)

uv tool install proton-to-icloud

With pipx

pipx install proton-to-icloud

From source

git clone https://github.com/abuchmueller/proton-to-icloud.git
cd proton-to-icloud
uv sync
uv run proton-to-icloud --help

Prerequisites

1. Export your Proton Mail — use the Proton Mail Export Tool to download your mailbox as .eml files.

2. Generate an App-Specific Password — go to appleid.apple.com → Sign-In and Security → App-Specific Passwords → Generate. This is required because iCloud IMAP does not accept your regular Apple ID password.

Usage

The Proton Mail Export Tool creates a folder structure like:

your.address@pm.me/
└── mail_20260223_210229/
    ├── messageId1.eml
    ├── messageId1.metadata.json
    ├── messageId2.eml
    ├── messageId2.metadata.json
    └── ...

Point --source at the mail_* directory (the one containing the .eml files). If you omit --source, an interactive folder picker launches — navigate with arrow keys, Enter to open a directory, Space to select, Esc to cancel.

Upload .eml files to iCloud

proton-to-icloud upload \
  --source "your.address@pm.me/mail_20260223_210229" \
  --mailbox "Proton-Import" \
  --email you@icloud.com

You'll be prompted securely for the app-specific password.

Options:

Flag	Description	Default
-s, --source	Directory containing .eml files (recursive). Interactive picker when omitted.	(picker)
-m, --mailbox	Base IMAP folder for subfolder routing and fallback	Proton-Import
-e, --email	Your iCloud / Apple ID email	(required)
-p, --password	App-specific password (prompted if omitted)	(prompted)
--direct	Route into native iCloud folders instead of subfolders
--dry-run	Scan only, don't connect or upload
--resume-from N	Skip the first N files	0
--no-create-mailbox	Don't auto-create the target folder

Folder Routing

When Proton metadata (labels.json and .metadata.json files) is present, emails are automatically routed to the correct folders based on their Proton labels.

Default mode — emails go into subfolders of --mailbox:

proton-to-icloud upload \
  --source "your.address@pm.me/mail_20260223_210229" \
  --email you@icloud.com
# → Proton-Import/Inbox, Proton-Import/Sent, Proton-Import/Archive, etc.

Direct mode (--direct) — emails go into native iCloud folders:

proton-to-icloud upload \
  --source "your.address@pm.me/mail_20260223_210229" \
  --email you@icloud.com \
  --direct
# → INBOX, Sent Messages, Archive, Junk, Deleted Messages, etc.

Proton Label	Default mode (--mailbox X)	--direct mode
Inbox	X/Inbox	INBOX
Sent	X/Sent	Sent Messages
Drafts	X/Drafts	Drafts
Spam	X/Spam	Junk
Trash	X/Trash	Deleted Messages
Archive	X/Archive	Archive
Unknown / no metadata	X (fallback)	X (fallback)

If no labels.json is found, all emails go to --mailbox (backward-compatible).

Split .eml files into batch folders

If you prefer to drag-and-drop smaller batches into Apple Mail instead:

proton-to-icloud batch \
  --source "your.address@pm.me/mail_20260223_210229" \
  --batch-size 1000

Options:

Flag	Description	Default
-s, --source	Directory containing .eml files. Interactive picker when omitted.	(picker)
-n, --batch-size	Files per batch folder	1000
-o, --output	Output directory for batch folders	<source>/batches
--move	Move files instead of copying	copy

Resume & Interruption Handling

The upload command saves a .imap_upload_state.json file inside the source directory after every 100 messages. If the process is interrupted (Ctrl+C, network drop, etc.), simply re-run the same command — it will detect the state file and offer to resume.

You can also manually resume with --resume-from N to skip the first N files.

Performance

In testing, throughput is approximately 1–2 seconds per message depending on file size and network conditions. For 50,000 messages, expect roughly 14–28 hours of upload time. An ethernet connection and a machine that can run uninterrupted is recommended for large imports.

Development

uv sync                        # Install deps
uv run pytest                  # Run tests
uv run ruff check src/ tests/  # Lint
uv run ruff format src/ tests/ # Format

Claude Code Integration

If you use Claude Code, this repo includes two project-level skills:

• /upload-guide — Interactive walkthrough that helps you construct the right upload command, choose routing modes, and handle long-running uploads.
• /diagnose-failures — Automated diagnostic workflow for investigating upload failures (header analysis, IMAP test matrix, root-cause suggestions).

These are optional — the CLI and this README are the primary interface.

License

MIT — see LICENSE.