Bug Fix: Only enable the Lockout email notification is the Daily Digest was previously disabled.
Bug Fix: Fix JavaScript error when loading the Notification Center on some systems.
Bug Fix: Don't store WP Error objects for mail errors preventing a fatal error for rare PHPMailer errors.
Bug Fix: Prevent error on upgrade warning the subject line was empty.
Bug Fix: Ensure file change notification is properly enabled/disabled on upgrade.
Bug Fix: Fallback to correct default subject lines.
Bug Fix: Don't enable all administrators as the recipients for emails where all custom email addresses did not have corresponding users.
Upgrade Routine: Properly enable lockout and file change notifications, uncheck all administrators as recipients when necessary.