cannot send emails from Outlook

i get this message when after some time has passed.

Task ' - Sending' reported error (0x800CCC6F) : 'Your outgoing (SMTP) email server has reported an internal error. If you continue to receive this message, contact your server administrator or Internet service provider (ISP).  The server responded: NetUI.SimpleButton._FireClickEvent {"UserActionID": 10111, "UserActionName": "NetUI.SimpleButton._FireClickEvent", "InputType": 2}'

no idea what it means i did change my VPN IP adress and that changed mothing. need some help. all other functions are fine,

so far i have all software is up to date, ran several deep system scans with defender and avast all were clean, restored outlook to a date several months ago... and ov course reset modem and several restarts of system./