Postbox
Postbox is a desktop email client for macOS that brings multiple mail accounts, search, organization, and writing tools into one app.
What is Postbox?
Postbox is a third-party desktop email application published by Postbox, Inc. for macOS and Windows. It is designed to manage multiple email accounts in one interface and supports common mail protocols such as IMAP, POP, and SMTP, including OAuth-based sign-in for services such as Google. Typical uses include reading and organizing large volumes of mail, searching across accounts, managing conversations, and composing messages with reusable snippets and templates. The app also offers workflow-oriented tools such as filters, keyboard shortcuts, quick actions, inline reply, and options for forwarding content to other services. On macOS, users may encounter it as an alternative to Apple Mail or Outlook, and it can be set as the default mail client. Postbox is still available to download, but its publisher states that it has been acquired by eM Client and is no longer in active development or available for purchase.
Key features
- Manage multiple email accounts in one desktop inbox
- Support for IMAP, POP, and SMTP email connections
- Fast search across messages, folders, and accounts
- Filters, rules, tags, and keyboard shortcuts for inbox organization
- Inline reply and send-and-archive workflow tools
- Reusable response snippets and placeholders for composing mail
- Theme and layout customization for different workflows
Review app leftovers with diCleaner
Inspect caches, support files, containers, and login items before cleaning.
Safety overview
Status: Mostly safe
Postbox is a legitimate email client from Postbox, Inc., but it handles sensitive mailbox data, saved account settings, and message content on the local device. Because email apps can store cached mail, attachments, and account metadata, review it carefully before removing data if you still need access to old messages. It also appears to be discontinued after acquisition, so long-term security and compatibility updates may be limited.
Recommendation: Keep it if you actively use Postbox for email or need access to mail stored in its local profile. If you no longer use it and have confirmed that any needed messages, accounts, and attachments are available elsewhere, removing the app is usually reasonable. Review stored local mail data before cleanup because deleting support files may remove offline messages and settings.
Common paths
/Applications/Postbox.app
Cache paths
~/Library/Caches/com.postbox-inc.postbox
Support paths
~/Library/Application Support/Postbox
Preference paths
~/Library/Preferences/com.postbox-inc.postbox.plist
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