Microsoft Outlook email account is not able to send e-mails , getting error Remote server returned '550 5.1.8 Access denied, bad outbound sender AS(42004)'

I am looking for a freelancer who can help me resolve an issue with my Microsoft Outlook email account. I am unable to send emails and I keep receiving the error message "Remote server returned '550 5.1.8 Access denied, bad outbound sender AS(42004)'". Skills and Experience: - Experience in troubleshooting Microsoft Outlook email issues - Knowledge of email server settings and configurations - Familiarity with error messages and their resolutions - Ability to communicate and work with email providers to resolve the issue Tasks: - Identify the cause of the error and propose a solution - Check and verify the Microsoft Outlook settings for any changes - Contact the email provider to inquire about the error and seek a resolution Please note that I have already tried sending emails from a different email client/platform, but the issue persists. Additionally, I have not recently changed the Microsoft Outlook settings, and I am unsure about how to check with my email provider regarding the error.