It took me a while to get this working on my PE-DVR16 but it's working great now and I'm pretty happy about it.
Here are some screenshots of the settings I used:
Google by default will block sending the emails because it considers the DVR a 'less secure app'. I used a secondary throw-away gmail account of mine to do the sending (that's what's under the username/password section on that screenshot) and had it send the notification to my primary email account (which I didn't have to change the security settings for).
To change the security settings on your gmail account to allow 'less secure' apps access:
1. Log on to https://myaccount.google.com/security
2. Go to 'Connected apps and sites'
3. Hit the switch on 'Allow less secure apps: OFF' to 'Allow less secure apps: ON'
That's what worked for me, hope it works for you