I have a LENOVO SYSTEM WINDOWS 10..I am the primary account holder..my account is ok the secondary account email is not ok..I have tried all sorts of combinations..no luck any ideas would be appreciated..
I can't help on the technical details but if its an option you should consider an email service not connected to a specific ISP. GMail / Outlook accounts are free and much more feature rich (security / spam / etc.) and access friendly. Plus if you ever decide to leave Optus they move with you.
We need a bit more detail to sort out your issues.
+1 with what Pete G said re not tying your email to an ISP. I switched to Gmail years ago which made changing ISP's painless.
Gmail works well with the Microsoft Outlook Email Client that comes with Windows 10. You can add as many Gmail accounts to it as you like.