Using New Outlook on Windows for personal email, calendar, and contact management
Since the account works in webmail, this appears to be an email hosting configuration issue rather than a problem with the Outlook apps themselves. The Windows error suggests that the outgoing SMTP server is either incorrect or is not authenticating the account properly.
Please ask the hosting provider to confirm the exact IMAP and SMTP server names, ports, encryption methods, full username format, and whether SMTP authentication or an app password is required. In Outlook for Windows, make sure My outgoing server requires authentication is enabled and uses the same credentials as the incoming server.
For Android, add the account manually as IMAP rather than selecting Outlook.com or Microsoft 365. The provider should also check the domain’s Autodiscover configuration, as an incorrect response from the hosting website can cause Outlook account setup to fail.
Until the provider confirms and corrects those settings, webmail may be the only reliable workaround.
Thank you and have a nice day