For this to work, you'll need:
1. a specific google account dedicated to just this purpose
2. an email to text service such as clicksend.com
Once you have this, go to Metatrader and click on Tools>Options>Email
Tick 'Enable email notifications'
For SMTP enter: smtp.gmail.com
In the SMTP login, enter your full gmail address.
This is where we need to go BACK to Gmail.
Go to
https://myaccount.google.com/apppasswords
Login as usual
Enter the name of the app that you wish to provide secure access to. In this case it's Metatrader.
Click CREATE.
Select and copy this password.
Go back to Metatrader.
Paste the password into the SMTP password.
This will allow FULL secure access to your Gmail account.