Sending SMTP email via our website error 535 5.7.139 Authentication unsuccessful

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ArisLacdao-2249 asked May 13, '22 JayceYang-MSFT commented Jun 1, '22

Sending SMTP email via our website error 535 5.7.139 Authentication unsuccessful

We're sending email from our website via SMTP using noreply@ourcompany.com.

We are using these settings to send email:

 MAIL_MAILER=smtp
 MAIL_HOST=smtp.office365.com
 MAIL_PORT=587
 MAIL_USERNAME=noreply@ourcompany.com
 MAIL_PASSWORD=xxxxxxx
 MAIL_ENCRYPTION=tls
 MAIL_FROM_ADDRESS=noreply@ourcompany.com
 MAIL_FROM_NAME="NOREPLY"

MFA is enabled, SMTP AUTH is enabled and we created an App password for noreply@ourcompany.com.

Upon sending an email we are encountering an error: 535 5.7.139 Authentication unsuccessful, the request did not meet the criteria to be authenticated successfully.

I already research how to fix this and I saw this question: https://docs.microsoft.com/en-us/answers/questions/512954/535-57139-authentication-unsuccessful.html

I can't set Enable security defaults to No because this account is company wide I want to keep this value to Yes. I just want noreply@ourcompany.com only to send emails via SMTP.

Then I saw that I can allow Legacy Authentication only on noreply@ourcompany.com via Conditional access maybe this will solve my problem. But when I go to Conditional Access I'm seeing this page:

Our account is not on Azure AD Premium. So we cannot send SMTP email unless our account is on Premium?

office-exchange-server-mailflow

screenshot-from-2022-05-13-16-03-52.png (95.7 KiB)

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JayceYang-MSFT · Jun 01 at 06:43 AM

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Answer 1 · 2022-05-13T10:33:02.12Z

michev answered May 13, '22 ArisLacdao-2249 edited May 13, '22

You cannot use App passwords for SMTP send, you'll have to disable MFA for the account you want to send with.

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ArisLacdao-2249 · May 13 at 11:24 AM

I have been researching this for the past 2 days. I've tried everything including disabling MFA. Its not working.

The thing is other people managed to make this work by enabling MFA and using App password.

The thing now that our account can't do is to Add Policies in Conditional Access. So what I'm validating now is do we need our account to be on premium in order to send SMTP from our website. Or is there another way to make this work even not on Premium.

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Answer 2 · 2022-05-16T06:07:31.303Z

KaelYao-MSFT answered May 16, '22 KaelYao-MSFT commented May 19, '22

Hi @ArisLacdao-2249

Please refer to this link: Basic Authentication Deprecation in Exchange Online – May 2022 Update

Here are some screenshots from the discussion:

If you would like to use basic auth, it is required to disabled Security Defaults.
Otherwise you may need to use modern auth instead.

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KaelYao-MSFT · May 19 at 07:57 AM

Hi @ArisLacdao-2249

Just checking in to see if above information was helpful. Please let us know if you would like further assistance.

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