Letterboxx

Letterboxx is a native macOS application designed to rescue email newsletters from the clutter of your inbox and turn them into a quiet, organized reading library. Instead of treating long-form content like actionable email messages, Letterboxx syncs with your IMAP accounts (Gmail, iCloud, Outlook, etc.) to fetch local copies of your subscriptions into a dedicated workspace.

Key Features

• Clean View — Strips out tracking pixels, intrusive ads, heavy HTML markup, and clutter to present long-form newsletters as clean, readable articles.

• Custom Letterboxxes & Auto-Delivery — Works like smart folders to automatically route incoming subscriptions into custom categories like Tech, Finance, or Weekend Reads.

• Highlighting & Recall — Allows you to highlight key passages in custom colors and quickly revisit saved insights across years of archived issues.

• Message Diagnostics — Includes detailed diagnostic tools for curious users to inspect sender identity, composition data, and HTML cleanup actions.

• Local & Encrypted Backups — Keeps your reading history saved locally on your Mac with optional encrypted backups so you never lose saved articles.

Why Choose Letterboxx?

If you subscribe to numerous Substack publications, industry roundups, or personal newsletters but dread reading them alongside work emails, receipts, and notifications, Letterboxx offers a dedicated 'reading shelf.' It separates consumption from communication, giving you a distraction-free environment with customizable themes (including dark, e-ink, and newspaper modes).