Also having email issues using version 6.9.3 and we are using Gmail (GSuite) and emails look like they are being sent but not being delivered. We get this error message that links to this page about Fixed Bounced or Rejected Emails BUT those email addresses do work and have been confirmed from outside X2.
That's one problem. Another major email related problem is we have templates in different folders and it's only showing the contents of one folder as a choice for templates and not any of the other folders. Be it campaign or email contact in workflow.