I have had the same issue here and there and when I worked with tech support from my distributor, we concluded it was the email service blocking the attachment or the ISP of where the NVR was not sending it out. For all the times I've had to use that feature, it has worked 50/50. I just can't say if it's the Dahua NVR not sending it or the ISP. Try sending to a different email service if you can. If you can, try using a Gmail account. I was told that would have the best luck.