Finished a site that is on Godaddy hosting, Domain is with Network Solution, and the Email is with Microsoft Office 365 Online. The issue was the customer wasn’t receiving emails from the forms on the site.
The form would send to any email address except the clients email address. I contacted Microsoft and got wonderful help.
The fix was to use their “@theirdomain.onmicrosoft.com” email address and not the alias.
Microsoft told me it took them 3 days to determine this fix.
I really hope this helps someone else out there….