Why has Microsoft Outlook stopped sending email from my bigpond.net.au account on my Pixel 8a phone?

Why has Microsoft Outlook stopped sending email from my bigpond.net.au account on my Pixel 8a phone? It was working well until 2 days ago, but now any email that I attempt to send from my Pixel 8a goes to the Draft folder on the Pixel 8a and stays there. Incoming mail is received to the bigpond.net.au account on my Pixel 8a without any issues. I have uninstalled the Outlook app, shutdown the phone, restarted phone, reinstalled Outlook app and done an advanced install of my bigpond.net.au account to ensure the imap/smtp settings, password etc are correct. If I go into the Draft folder on my laptop and send the email parked in the Draft folder on the Pixel 8a from the laptop it transmits successfully and it will disappear from the Draft folder on my Pixel 8a. Puzzlingly, email deleted from the Draft folder on the laptop does not disappear from the Draft folder on the Pixel 8a - but that's a minor matter in the scheme of things!