@David-TP 

hi. I had tried this previously by removing the old Main deco. 
I have now removed both M5s from the network and did still get a couple of alerts. Then it went quiet so I added the M5s back one at a time. 
Each time I got a couple of alerts then it stopped. 
I have added both now and have still had a couple of alerts but nothing like the number I was getting. 
ill monitor and see how it goes. 
 

FYI I didn't use the button reset just deleted from the network which deco says is the same as a factory reset. 
Thanks for your rwaponse
 

  @David-TP 

hi

i am still getting device connection emails 

nothing has really changed tbh. 
The deluge of alerts from the other day was due to an issue with the firmware on x50 and the guest network which I use for my IoT devices. These kept on disconnecting and reconnecting. A new firmware was issued that largely fixed this issue although I still get a few network disconnections on the guest network. 

But the fact remains that I cannot stop the email alerts for any device connecting to the network. 
e.g.  if I disconnect my phone from the network then reconnect I get a new decive alert. 
 
Any further suggestions please?

  @David-TP 

hi. I have submitted logs and images of the email alerts and app notifications I am receiving. 
I get way more emails than app notifications. Are the emails generated by the App or the TPlink cloud. Either way the settings I have made to turn off email notifications are being ignored.  
I have also turned off private WiFi address although I am jot happy about leaving this off on a permanent basis. 
please advise next step pleaae

  @alsaolem  did you end up resolving this issue, I am having the exact same thing. 

  @Jay1982 hi

yes I have managed to get the emails to stop. 
In the end, I did a full factory reset of all deco units and started from a clean install. 
Need to do them all at once so it's like an out of box install.

hope it works for you

  @alsaolem great thanks for letting me know. I was obviously trying to avoid that but if it stops the notifications then I guess I'll have to do it. 

  @Jay1982 I had the same mindset as I thought it would save time to keep the config. But run out of time and enthusiasm to get to the root cause / fix. Hence the rebuild. Frustrating but the rebuild fixed it for me