@Robert_James
some time ago Google made changes to their security protocol for SMTP and was no longer allowed to just plug in credentials and it work. You have to set up the app and they no longer allow lesser secure apps. If you insist on using Google I suggest you follow their instructions.
Here is a third-party instruction on how to use Google SMTP.
I am with @Brady. I use sendgrid. Here is a little tool I created to help me test my SMTP connection. Drop this file into the interface folder and access it from the browser HTTP://localhost/interface/testmail.php. It will show you what is happening with your SMTP connection and then you will a better chance of fixing it.
testmail.php (1.6 KB)