2

I am a corporate employee. as part of my work I need to send emails from my C# code.

with the below code I am able to send emails successfully using less secure gmail ID. But I am not able to do same with my corporate outlook exchange based email ID. I get below exception.

" 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, SmtpClientAuthentication is disabled for the Mailbox. Visit https://aka.ms/smtp_auth_disabled for more information. [BN9PR03CA0659.namprd03.prod.outlook.com]"

what I should do ? is there a way I can make my corporate outlook exchange email ID less secure to enable to sending emails. (Like I did for gmail.)

below is the code I am using.

MailMessage message = new MailMessage(from, to);

        string mailbody = "In this article you will learn how to send a email using Asp.Net & C#";
        message.Subject = "Sending Email Using Asp.Net & C#";
        message.Body = mailbody;
        message.BodyEncoding = Encoding.UTF8;
        message.IsBodyHtml = true;         
        client.EnableSsl = true;
        client.UseDefaultCredentials = false;
        client.Credentials = new NetworkCredential("name@corporatecompany.com", "$password");            
        client.Host = "smtp.office365.com";
        client.Port = 587;
        client.DeliveryMethod = SmtpDeliveryMethod.Network;          
        try
        {
            client.Send(message);
        }
Eugene Astafiev
  • 34,483
  • 3
  • 16
  • 35
Krishna Prasad
  • 21
  • 1
  • You need to make sure the smtp address is correct. It may be different for your org although using O365 and may be port#. Check with your corporate Email managing team/AD team whoever is responsible for this and try again. – Ak777 Jan 12 '22 at 04:52
  • Does this answer your question? [5.7.57 SMTP - Client was not authenticated to send anonymous mail during MAIL FROM error](https://stackoverflow.com/questions/30342884/5-7-57-smtp-client-was-not-authenticated-to-send-anonymous-mail-during-mail-fr) – Eugene Astafiev Jan 12 '22 at 11:52
  • There are a bunch of similar posts here. Have you checked existing posts with the same error message at SO? – Eugene Astafiev Jan 12 '22 at 11:53

1 Answers1

0

You need to make sure the smtp address is correct. It may be different for your org, although using O365 and may be port#. Check with your corporate Email managing team/AD team whoever is responsible for this and try again.

It may be that the smtp host can be your org domain host instead of generic one. I am suggesting based on experience of what we have, as we also use O365 for our corporate emails and I have our smtp host as "mail..com" with port#. And there could be a service account which has given appropriate permissions to use as otherwise, it would become less secure to use the smtp relay.

Ak777
  • 303
  • 7
  • 16