From 10.30am this morning Out look has been unable to get email from zoho pop account

From 10.30am this morning Out look has been unable to get email from zoho pop account

Keep getting this message

'Outlook cannot find the server. Verify the server information is entered correctly in the Account Settings, and that your DNS settings in the Network pane of System Preferences are correct.'

Any ideas what's changed ? - my settings have not...

Many thanks