Happens all the time. Email server is down, or can't get access to company email where you are. I got an email from the CFO of the company I work for the other day. It was from his personal email account because he doesn't have the work email on his iPad. Same thing happened with the HR person last year when she was on vacation and an employee needed to be fired and couldn't wait until she got back. She didn't have her work laptop with her that day and she needed to be able to review all the documentation.
Your email domain ends up on a block list used by your client/vendor's spam blocker. Can be a real pain in the butt to get it removed. Until then use a domain that's not on the list, most likely a personal account.