To enable Spotlight indexing of email in Postbox, go to Preferences | General and check "Allow Spotlight to search messages".
Messages are added to the Spotlight when Postbox's internal indexer is run on messages, which will happen automatically when Postbox detects that your computer is idle. To immediately get all of your messages into Spotlight, navigate to the Tools menu > Indexing > Index All Messages...
Search by Topic
Postbox allows you to use Spotlight to search for Postbox messages by Topic. For example, you type the following into the Finder search bar: "keyword:marketing" to find all messages that have the Topic "marketing." You can then create a Smart Folder and save it to your Finder sidebar.
To enable this functionality please perform the following steps:
- Make sure the Postbox app resides in Applications folder on your Mac.
- In Postbox, under Preferences > General check the "Allow Spotlight to search messages" option.
- Make sure that only ONE copy of Postbox is on your hard drive or any mountable volume. Use Spotlight to search for "Postbox" with Kind: Application to find any and all copies of the Postbox application. If you have partitioned your drive to manage more than macOS installs, only ONE copy of Postbox can exist (otherwise Spotlight might use the wrong importer).
- You must re-index your mail messages by going to Tools > Indexing > Index All Folders... You may wish to perform this last step overnight to avoid work interruptions.
- Quick Look for files found via Spotlight is currently not supported, but you can double-click the file to open it in Postbox.
- The Spotlight files are located at: ~/Library/Caches/Metadata/Postbox/
- Unchecking "Allow Spotlight to search messages" can temporarily cause Postbox to "beach ball" (hang) while Postbox removes all messages from Spotlight.
- Spotlight indexing does not work with multiple Postbox profiles.