I am getting an error for one of the business’ application when trying to send an email.

Error message:

SMTP.SendEmailV2 failed: { "status": 403, "message": "The SMTP server 'smtp.office365.com' requires a secure connection or the client was not authenticated. Ensure you are using SSL connection and check your account's security settings (if you have enabled 2-step verification, try to use App password, otherwise, turn on access for less secure apps).rnclientRequestId: b340bfd1-9f8f-4243-a41d-19c5b67b6f2a", "source": "smtp.office365.com:25", "errors": [] }

The error only occurs with one of our applications, although all of the applications uses the same SMTP connection. Also although the app was recently published from our TEST environment to Production, however, the issue is only occurring in Production.