QNAP Security VioStor NVR (Version: 3.5.1) - Manual (Page 204)

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(4) Email
To receive an instant email alert when an event is triggered, enter the SMTP settings.
Multiple email addresses can be entered as the recipients. Snapshots of multiple
channels (IP cameras/video servers) can be attached to the alert emails.
Click ‘Select from the list’ to select an action setting which has been configured
before.