Thank you very much.
1.What did you do when you encountered the error message?. I didn't do anything.
2.Can you send/receive emails by using the Office 365 account? Yes, I can through giant-move.us
3.Can you login to team site successfully? yes, I can.
I will check that: Additionally, please refer to the steps below to check if you have changed the name server to Office 365:. But I think I did in first place when I migrated my domain name to 365.
Regards
Hugh