Issue while configuring SMTP using O365

Question

Hi,

I cant able to send mails using SMTP via O365.I have enabled the SMTP AUTH in mail apps.While i try to send mails through SMTP got the below Error.

"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 5.7.3 Authentication unsuccessful [SG2PR03CA0140.apcprd03.prod.outlook.com]"

Answer 1

Is the account MFA enabled?

Answer 2

Hi @Suganthan Kumar (AP)

Please refer to this link for troubleshooting: Fix issues with printers, scanners, and LOB applications that send email using Microsoft 365 or Office 365

There are four possible causes of this issue:

1. SMTP AUTH is not enabled on the mailbox being used
2. MFA is enabled on the mailbox
3. Azure Security Defaults is enabled in the tenant
4. The user is included in a Conditional Access policy which blocks Legacy Authentication

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