Gmail SMTP Functionality Not Enabled
I ran into this issue yesterday when trying to add a new non-gmail address to my Gmail account:
You must send through SMTP servers when you send as example.com. However, this functionality is not available for your account. Please contact your domain administrator.
Try the following fix:
In google apps and under Gmail
Click Advanced settings
Under “Allow per-user outbound gateways” – Disable the checkbox and re-enable it again (or just enable it if it is initially disabled).
This should activate this setting although the downside of this is that it could take up to 24 hours to propagate in full
It should solve the error.
Please refer to link: http://www.sparkcreativeworks.com/gmail-smtp-functionality-not-enabled/