Cant set up New Outlook with Telatrs IMAP

The error INVALIDCREDENTIALS TEMPORARILYUNAVAILABLE when adding an IMAP account in new Outlook for Windows usually indicates a problem with how the mail provider is authenticating the account, not with Outlook itself. For many third‑party IMAP providers, new Outlook requires either an app password or a correctly configured IMAP/SMTP profile.

Use these steps to work around the issue and get the account working:

1. Confirm whether an app password is required
   Many providers (including some ISP mailboxes) require an app password for email apps instead of the normal sign‑in password, especially if multi‑factor or modern security is enabled.
   • Sign in to the Telstra/BigPond webmail or account portal.
   • Check their help for “app password” or “third‑party email app password.”
   • If they support it, generate an app password and use that in Outlook instead of the normal password.
2. If automatic setup fails, configure the account manually in classic Outlook
   New Outlook has more limitations with some third‑party IMAP providers. If the account cannot be added there, set it up in classic Outlook using manual IMAP settings:
   1. Open classic Outlook for Windows.
   2. Select File > Add Account.
   3. Enter the email address, choose Advanced options, then select Let me set up my account manually.
   4. Choose POP or IMAP.
   5. Enter the IMAP/SMTP server names and ports provided by Telstra/BigPond.
   6. Enter the account password (or app password if required), then choose Connect.
   7. If setup fails, choose Change Account Settings and verify the IMAP/SMTP details against the provider’s documentation, then select Connect again.
   8. Choose Done.
3. If classic Outlook never prompts for a password
   When adding the IMAP account in classic Outlook, make sure Require logon using Secure Password Authentication (SPA) is unchecked on the IMAP details page. If needed, recreate the profile from Control Panel > Mail > Email Accounts > New and follow the wizard, entering the password when prompted.
4. If the provider enforces IMAP only
   For some mailboxes (similar to Outlook.com in the documentation), the mailbox must be configured as IMAP to import or sync correctly. Ensure the account type is IMAP, not Exchange or Microsoft 365, when setting it up.

If the account works in classic Outlook but still cannot be added in new Outlook on that PC, continue using classic Outlook for that mailbox until the provider or Outlook updates improve compatibility.

References:

• Add an email account to Outlook for Windows
• Troubleshoot Outlook email setup
• Fix problems importing an Outlook .pst file
• Error, "You may need to make an app password," when you add an account or send/receive email from some third-party email accounts