Doing this requires editing an file in an invisible folder — not exactly user-friendly! Here's how. In the Finder, choose Go > Go to Folder, enter the full path of the folder you're syncing followed by /.sync (such as /Users/joe/Documents/.sync) and click Go. In the Finder window that opens, double-click the file IgnoreList to open it in TextEdit (or your default app for text files). Add the file(s) or folder(s) you want to exclude at the end of the list, one item per line. (You can use the wildcards * and ? to indicate patterns, such as IMG_*.jpeg.) Save the file. From now on, the designated items will no longer sync, but BitTorrent Sync doesn't remove any copies that had already synced to your other devices — you'll have to do that manually.
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