You had better use Gmail, not yahoo or Hotmail.
1. Connect the NVR to the router by ethernet cable.
Pay attention: there are 4 ethernet ports at the back of NVR which includes 3 LAN port and 1 WAN port. Please use WAN port to connect the router, not the LAN port.
2. Check P2P status and make sure it is online.
3. Go to Video detection set up. Enable it and tick the Email Notice option.
4. Please log in to your Gmail account.
5. Please open the website below
6. Please select Less Secure APPs and tick turn on.
7. Please set up the email in the NVR setting like the picture below. If the mail test succeeds, it is working.
SMTP server: smtp.gmail.com
Port: 587 / 465.
Username: your Gmail account
Password: your Gmail password
Encryption Type: SSL
Sender: your Gmail account
Sendee: the receiver and can be any email