I did a terrible mistake, I tried to send an email ( to my personnal email) using node red, but Gmail assumed that my account is hacked, and blocked node red,now I keep loosing connection to the server every few seconds even after allowing less secure apps to access my Gmail account and uninstalling and reinstalling Node-Red , what is the solution ? 
please help me.
Gmail has no relationship to you losing access to Node-RED, they are different issues.
All Google have done is probably just sent that single email to Junk. At worst, they will have blacklisted the source IP address. Depending on where you are running Node-RED this might be your home broadband. But that blacklisting only applies to email, nothing else.
You should look at the Node-RED logs and see if there are any errors. If not, check out the developer tools in your browser - press F12 to see them. Look at the console tab and see if there are any errors there.
You're right, I just realized that I already had this error before using email node and the only solution I had is to uninstall everything and delete all related files (node.js and npm) than reinstall it all,this is the error I'm having, if you have a better idea than mine to solve it 
