Outlook.com Authentication

Question

Hello,

I am using free outlook.com account to setup a cellular modem to send email. I set APP password for authentication. however, I still get following error from cellular modem log:

recv:'535 5.7.139 Authentication unsuccessful, basic authentication is disabled. [Moderator note: PII removed]'

In order to use APP password, do I need verify sim card phone number first through 2-step verification?

Thanks

Answer 1

Hello support, 

Thanks for your post in the Microsoft Q&A forum. 

I realize that you've encountered an "Authentication unsuccessful" incident (Error 535 5.7.139) with your cellular modem, and I understand the frustration when a previously working setup fails. 

I've reviewed the Q&A Assist response. While checking credentials is important, I'd like to add more critical information. The error often occurs due to outdated server settings, especially following Microsoft's security updates. 

You are correctly using an App Password, which remains the supported method for devices like modems that don't support modern OAuth2 authentication. However, the server must be configured correctly. 

Please reconfigure your modem with these exact Outlook.com SMTP settings: 

• SMTP Server: smtp-mail.outlook.com 
• Port: 587 
• Encryption: STARTTLS (or TLS) 
• Authentication Method: Username and Password (use this option, then enter your App Password) 
• Username: Your full Outlook.com email address. 
• Password: Your 16-character App Password. 

You can verify these settings in the official guide: POP, IMAP, and SMTP settings for Outlook.com. 

If the error persists with the correct settings:  It may indicate a compatibility issue. Please check: 

1. Firmware Updates: Visit your modem manufacturer's website for any firmware updates that improve email client compatibility. 
2. Authentication Options: In your modem's settings, see if there is a dropdown for "Authentication Method" that includes "OAuth2" or "Modern Auth." If available, you would need to set up authentication through a separate, browser-based login flow. 

To help me investigate further, could you please provide the model number of your cellular modem? 

Please update the SMTP settings first and let me know the result. 

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Answer 2

To use an app password for authentication with your Outlook.com account, you do not necessarily need to verify your SIM card phone number through two-step verification. However, enabling two-step verification is a prerequisite for generating an app password. Once two-step verification is set up, you can create an app password that can be used in applications or devices that do not support two-step verification.

The error message you are receiving indicates that basic authentication is disabled, which is a common issue when trying to use older authentication methods. Ensure that your cellular modem supports the use of app passwords and that you are entering the app password correctly. If the modem does not support modern authentication, you may need to check for updates or consider using a different method for sending emails.

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References:

• Migrating your Outlook.com account to Microsoft 365 or Office 365
• Automate email accounts with two-step verification