There is much better/secure way to allow non-Google apps (like ELK) to send emails using a Google account. You can define an “app password” and use that in ELK. The “app password” is auto-generated by Google and it contains 16 chars. There is no need open your gmail account to potential hacking. App password is very secure.
I am using app password with ELK. The process to define app password is defined here:
https://support.google.com/mail/answer/185833?hl=en-GB
Hope it helps!
MKG