I Got Tired of Downloading Email Attachments One by One, So I Built a Desktop App for It

#opensource #python #api #automation

Picture this: 200 invoices in your inbox, scattered across six months of emails, and accounting needs all of them in a folder. Today. Gmail's UI gives you exactly one way to do this — open email, click attachment, download, repeat. Two hundred times.

I refused. So I built Email Attachment Downloader — an open-source desktop app that bulk-downloads attachments from Gmail and Outlook with filtering, auto-renaming, and a modern dark GUI. Python, MIT licensed, runs on Windows, macOS, and Linux.

What it does

The workflow is simple: connect to your inbox over IMAP, filter, preview, download. But the details are where it earns its keep:

Filter by sender, subject, and date range — invoices@company.com + "invoice" + Jan–Mar gets you exactly the emails you need, with a built-in calendar picker for dates
File type selection — download only PDFs, or only spreadsheets, or images, documents, presentations, archives — your call
Preview before download — see every matching email and its attachments, deselect the noise, then pull the trigger
Auto-renaming patterns — this is my favorite part. invoice.pdf becomes 2024-01-15_invoice.pdf or john_2024-01-15_invoice.pdf automatically. Anyone who's ended up with invoice.pdf, invoice(1).pdf, invoice(14).pdf knows the pain this solves
Threaded downloads — attachments download in parallel without freezing the UI, with a real-time progress bar and activity log

The stack

Python 3.10+ with plain IMAP (imaplib) for email access — no Gmail API credentials, no OAuth app registration, no Google Cloud Console. An App Password and you're in
CustomTkinter for the GUI — if you think Tkinter apps have to look like Windows 95, CustomTkinter will change your mind. Modern dark theme, clean widgets, zero web stack
tkcalendar for the date picker

The architecture is deliberately modular — email_client.py handles IMAP, downloader.py handles extraction and saving, renamer.py is pure renaming logic.

Security — because it's your inbox

An app that asks for your email password deserves scrutiny, so here's the deal:

Your password is never stored — it lives in memory for the session only
It works with App Passwords (recommended), so your real password never touches the app
All connections use SSL/TLS (IMAP over port 993)
The app is read-only — it never modifies or deletes emails
And it's open source, so you don't have to take my word for any of this — read the code

The README has step-by-step App Password setup guides for both Gmail and Outlook, because that part trips up everyone the first time.

Honest limitations

It searches your INBOX folder over IMAP — if your invoices live in a label/subfolder, or your provider doesn't do IMAP, you're out of scope for now. And it's a desktop tool by design: no cloud, no web version, your credentials and files stay on your machine. I consider that last one a feature, but your mileage may vary.

There's a Windows installer if you just want to use it, or clone and pip install -r requirements.txt if you want to poke at the code. Issues and PRs welcome.

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