Enable smtp access to your gmail account

So quite some time ago Gmail blocked insecure smtp access to your gmail account, even when you turned on tls which previously had been working for a few years.

There is however a workaround for this where you create an email-only login to your gmail account:

Open My Account from the Google menu:

Click the Signing in to Google link:

Click App passwords:

You're prompted to verify your login:

Follow through the options here, under Select app choose Mail (or other Google function -- say Youtube if you're setting up a special login for a media box), select a device from the drop down list or choose Other, then click Generate:

Copy and paste the created password into your device. SMTP settings are smtp.gmail.com:465, tls enabled, user is your gmail email address.

HTH!