Hi @Ali Zahid
For better research, please provide more details about this case:
What is your account type? A Microsoft 365 account?
Can't all emails outgoing?
What is your Outlook client version? Please make sure to update to the latest version.
According to this error message, typically indicates a mismatch between the authentication methods that your email client (Outlook) supports and what your email server requires.
Here are a few steps you can try to resolve this issue:
- Check the Authentication Settings: Ensure that your Outlook is set up to use the correct authentication method required by your SMTP server.
- Check for Email in Outbox: Sometimes, having an email stuck in the outbox can cause issues.
- Use Control Panel to Set Up Account: If the above steps don’t work, you can try setting up your email account through the ‘Control Panel’ > ‘Mail’ > ‘Email Accounts’.
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