Configure the destination to the email alert.
# config alertemail setting
set username "firstname.lastname@example.org"
set mailto1 "email@example.com"
Configure the Gmail account to use an App Password:
An App Password is a 16-digit passcode that gives a less secure app or device permission to access the Google Account.
App Passwords can only be used with accounts that have 2-Step Verification turned on.
For more information on how to set up App Password on the Google account, refer to the below document:
Following this, it will be possible to send alert mails.
Test this with following command:
# diagnose log alertmail test