SMTP Settings not authenticating

Your original credentials look correct for GMail, it would be port 587 with SSL checked.

There’s a post here regarding the same error response from GMail. I think maybe check your recent activity on Google as I believe any new connections are flagged up here.

Also try the link below which seemed to be the solution on the other post.

https://accounts.google.com/b/0/DisplayUnlockCaptcha