Dear West Gardner,
Good day!
Thank you for posting to Microsoft Community. We are happy to assist you.
As per the description you have shared, we understand that you have a concern with setting up SMTP.
To better understand the issue and provide possible solution we need more details from you, please kindly provide us the following information. Thank you.
- May I please confirm if you are using Microsoft 365 business email account (such as ******@compandomain.com), Microsoft Personal account (Outlook.com, hotmail.com or live.com) or third-party email account?
- May I please confirm if you are using Exchange, IMAP or POP email account?
- May I please confirm if SMTP is enabled for your mailbox?
- May I please double confirm if you want to set up SMTP-client submission, SMTP relay or Direct send?
Typically, for SMTP-client submission, we use smtp.office365.com as SMTP server/host. You can refer to the screenshot below.

Therefore, SMTP User ID refers your email address (mailbox), and SMTP Password refers your email address(mailbox) password that you are using for signing into your account.
For SMTP relay, we use yourdomain-com.mail.protection.outlook.com as SMTP server/host. You can refer to the screenshot below.

For direct send, we use contoso-com.mail.protection.outlook.com as SMTP server/host. You can refer to the screenshot below.

So that, you may change your SMTP server/host based on the above example and check if there is any difference.
For additional information, you can refer to How to set up a multifunction device or application to send email using Microsoft 365 or Office 365 | Microsoft Learn
We look forward to your update. Kindly note that the above requested information is required for further analysis and troubleshooting of your situation. Your patience and cooperation are much appreciated.
Thanks for your precious time.
Have a nice day!
Sincerely,
Libeamlak | Microsoft Community Moderator