Using classic Outlook for Windows in business environments
Hello James Chemp1,
Welcome to the Microsoft Community.
I understand that you encountered an error when sending an email.
Thank you for providing the error message. This type of error is usually described as "You do not have the permission to send the message on behalf of the specified user."
The cause of this issue is often due to a mismatch between the actual email account you are using to send the email and the email address specified in the "From" field.
I suggest you check the connection status of your Hotmail account in your Classic Outlook.
When composing a new email, select a folder or email from your Hotmail account. If the default settings are unchanged, this will ensure that the email address in the "From" field matches the current sending account.
If you still encounter issues, check if your account works properly through Outlook Web.
Please feel free to let me know if you have any further updates, thanks.
Best Regards,
Zachary.W - MSFT | Microsoft Community Support Specialist