Failed to authenticate password using codeigniter and gmail
If you are using Google account
UPDATE: now you need to enable "less secure apps" on your Google Account
You would need to go to your account settings https://www.google.com/settings/security and you would need to enable Access for less secure apps which helps to use the google smtp for clients.
May be this will help!!
This is my experience.Already enabled less secure apps on my Google Account and successfully authenticated password using Codeigniter and Gmail. And after a few months of disuse I'm on the CI system again and it seems to fail to authenticate the password, be aware that Google will automatically disable this setting when not in use. It's time for you to reactivate it.