SMTP Authenication Failure - 5.7.57 and 5.7.139

Question

I am attempting to enable a Multi-function device to scan documents and send via email.

However, in testing the SMTP settings of my account I get the following error message:

Send-MailMessage : The SMTP server requires a secure connection or the client was not authenticated. The server
response was: 5.7.57 Client not authenticated to send mail. Error: 535 5.7.139 Authentication unsuccessful, the
request did not meet the criteria to be authenticated successfully. Contact your administrator.

I have taken the following steps already:

1. Referenced this article (https://learn.microsoft.com/en-us/Exchange/mail-flow-best-practices/how-to-set-up-a-multifunction-device-or-application-to-send-email-using-microsoft-365-or-office-365?redirectSourcePath=%252fen-us%252farticle%252fhow-to-set-up-a-multifunction-device-or-application-to-send-email-using-office-365-69f58e99-c550-4274-ad18-c805d654b4c4#how-to-set-up-smtp-auth-client-submission) and determined the need to enable SMTP AUTH
2. Referenced this article (https://learn.microsoft.com/en-us/Exchange/clients-and-mobile-in-exchange-online/authenticated-client-smtp-submission) and enabled SMTP AUTH for the account in question (and then later the whole organization in attempts to resolve)
3. Referenced this article (https://support.microsoft.com/en-us/account-billing/manage-app-passwords-for-two-step-verification-d6dc8c6d-4bf7-4851-ad95-6d07799387e9) to create an app password for the sending account
4. Attempted direct login from the device
5. Attempted using the following powershell command to send (with respective email addresses changed)

$cred = get-credential
$body = "This is a test email"
Send-MailMessage -To "testTO@test .com" -from "test@test .com" -Subject 'Test message' -Body $body -BodyAsHtml -smtpserver smtp.office365.com -usessl -Credential $cred -Port 587

I have tried using the get-credential feature as well as passing through a secured connection. I have tried multiple accounts all with the same result.

I have also tried to disable the Active Directory Security Defaults, but cannot enable a Custom Access Rule because I do not have the licenses.

Answer 1

@Lance Luttrell
Thank you for your post!

Adding onto what @Andy David - MVP said and based off your error message - Send-MailMessage : The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.57 Client not authenticated to send mail. Error: 535 5.7.139 Authentication unsuccessful..., I found a few Q&A threads that might help point you in the right direction.

Following the - Error: Authentication unsuccessful documentation:
Can you reference troubleshooting steps 3 and 4 to see if that helps. As @Kael Yao mentions, these settings would block Legacy Authentication. For more info.

Additional Links:
535 5.7.139 Authentication unsuccessful - Q&A
535 5.7.139 Authentication unsuccessful - Microsoft 365 and Office Community

If you have any other questions, please let me know.
Thank you for your time and patience throughout this issue.

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Answer 2

If MFA reg is required for the account ( And it is Active Directory Security Defaults), then this wont work.