Send personalized bulk emails from your own machine, using your own SMTP account. No subscriptions, no third-party servers, no data leaving your computer.

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Why bit-by-mail

Most bulk email tools are SaaS platforms, where you upload your recipient list to someone else's server and pay a monthly fee for the privilege. bit-by-mail flips that: it's a lightweight local app that runs on your machine and sends through your own email provider. Your data stays yours, and there's nothing to pay for.

Features

• Local and private — runs entirely on your machine; nothing is uploaded anywhere
• Bring your own SMTP — works with Gmail, Outlook, Yahoo, or a custom domain; supports multiple accounts with a default sender fallback
• Dynamic personalization — one template, personalized per recipient using variables from your CSV ({{FirstName}}, {{InvoiceAmount}}, etc.)
• Personalized attachments — send different files to different recipients in the same campaign (certificates, invoices, reports)
• Rich text or raw HTML — use the WYSIWYG editor, or drop into a Monaco-based HTML editor for full control
• Preflight checks — simulates the send beforehand to catch missing variables, missing attachments, or invalid addresses
• Reusable libraries — save recipient databases and templates so you're not rebuilding them every time
• Live analytics — real-time dispatch logs, success/failure tracking, and exportable CSV delivery reports

Getting Started

Install

pip install bit-by-mail

Requires Python 3.9 or later.

Launch

bit-by-mail
# or, for short:
bbm

The app opens automatically in your browser at http://localhost:8888.

Connect your email account

1. Go to Settings in the sidebar.
2. Click Add Account and enter your SMTP details (e.g. smtp.gmail.com, port 587).
3. Enter your email and password.

Using Gmail? Google blocks sign-ins with your regular password. Generate an App Password instead and use that.

Prepare your recipient list

Recipients are loaded from a CSV file with a header row.

Column	Required	Notes
Name	Yes	Used for personalization
Email	Yes	Recipient address
AttachmentFile	No	Separate multiple files with ;
anything else	No	Any extra column becomes a placeholder automatically

Example:

Name	Email	AttachmentFile	TicketType
John Doe	john@example.com	john_pass.pdf	VIP
Jane Smith	jane@example.com	jane_pass.pdf; map.png	Standard

Run a campaign

1. Campaigns → New Campaign
2. Upload your CSV, or import a saved database
3. Write your subject and body, using placeholders like {{Name}} or {{TicketType}}
4. Check the Preview panel to confirm placeholders render correctly
5. Run Preflight to catch problems before sending
6. Click Start Sending

Advanced

Asset Library — store image URLs (including Google Drive links) and drop them into your templates without re-uploading each time.

Throttling — add a delay (in seconds) between sends in Campaign Settings to stay under provider rate limits and avoid spam filters.

Resume on failure — if a campaign is interrupted, bit-by-mail remembers who's already been sent to. Hit send again and it only processes the recipients still marked PENDING.

Troubleshooting

• Emails aren't sending — double-check your SMTP host and port, and confirm you're using an app password rather than your account password if your provider requires one.
• Placeholder shows up literally in the email (e.g. {{FirstName}}) — the column name in your CSV doesn't match the placeholder exactly; names are case-sensitive.
• Attachment not found errors during Preflight — check that file paths in AttachmentFile are correct relative to where you're running the app, and that multiple files are separated by ; with no typos.

Rich Text/HTML Editor with Live Preview & Placeholders

Contributing

Issues and pull requests are welcome. If you run into a bug or have an idea for a feature, open an issue on GitHub.

License

See the LICENSE file for details.