Sending emails out of QuickBooks desktop has a hiccup?

Chat support on QuickBooks end says QuickBooks is being blocked from your email provider.  to go to online email service (Homestead) review your settings and filter preferences.   

Where are such settings and filter preferences that I may review?

I use Gmail to receive and send.  Now Gmail can't authenticate?  Authentication error. Check your username and password.
Server returned error: "434 eQpevUcZ6V6WM - <??> sender rejected AUP#SNDR , code: 434"

RESOLVED: I deleted the account from the Gmail [Accounts and Import] from the "Send mail as" section.  Re-created it and it worked.