@linda123456 Have you googled the error and tried any of the solutions?
Does your device have another application that you can setup email to do some testing or maybe try setting up a new email account in Outlook?
If you have authentication ticked for your outgoing mail server have you tried unticking it? Do you use any programs or addins or plugins that may interfere with Outlooks operation?
Edit: You didn't add a VPN or new antivirus recently?