Postbox
Postbox is a desktop email client for macOS that brings multiple mail accounts, message organization, search, and offline access into one app.
What is Postbox?
Postbox is a desktop email client for macOS and Windows that helps people manage multiple email accounts in one place. It is designed for users who want a dedicated mail app with stronger organization and writing tools than a basic web inbox. Common tasks include reading and sorting messages, searching large mail archives, composing professional email, and working with IMAP or POP accounts. Postbox supports offline access for synced mail, customizable layouts, filters and rules, keyboard shortcuts, and integration with macOS Contacts. It can also be set as the default mail app for handling email links. Postbox was published by Postbox, Inc., and its website notes that the product has been acquired by eM Client and is no longer in development or available for purchase.
Key features
- Manage multiple email accounts in one desktop inbox
- Search messages quickly across folders and mail archives
- Organize mail with filters, rules, tags, and folder actions
- Compose and reply to email with advanced writing tools
- Work with synced mail while offline and send changes later
- Customize the layout, panels, and viewing style to match your workflow
- Use keyboard shortcuts and quick actions for faster inbox triage
- Integrate with macOS Contacts and use it as the default mail app
Review app leftovers with diCleaner
Inspect caches, support files, containers, and login items before cleaning.
Safety overview
Status: Mostly safe
Postbox is a legitimate desktop email application, but it handles sensitive data such as email content, attachments, contacts, and stored account credentials. On macOS, access to Contacts or Automation can be consistent with its email and integration features if you use them. Because the product is no longer in development, security fixes and compatibility updates may stop, so an older installation can become a higher risk over time. If you still use it, review which mail accounts are signed in and make sure you are comfortable keeping archived mail stored locally.
Recommendation: Keep Postbox if you still rely on it for daily email or need access to its local mail archives and account setup. If you no longer use it, removing it can free disk space and reduce exposure from keeping an unsupported email client installed. Before uninstalling, confirm that any important local mail, filters, and account data have been migrated or backed up.
Common paths
/Applications/Postbox.app~/Library/Application Support/PostboxApp/Profiles
Support paths
~/Library/Application Support/PostboxApp
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