Using New Outlook on Windows for professional communication and productivity
I also have the same problem. After switching to Outlook last year everything worked well, but over the last 3 months or so I regularly get the undeliverable message below. Sometimes I can send successfully and sometimes not. It seems random and getting worse. I have a btinternet email address.
I'm not that great at tech so please advise.
Thanks
Trevor
Technical details
SmtpSubmissionPermanent5XXException: Smtp submission failed. Server 'mail.btinternet.com' Port '465'. --> Unexpected SMTP server response. Expected: 235, actual: 535, whole response: 535 invalid user ID or password from 52.98.158.253
Failure code: cf24