Subject: SMTP error when calling using anonymous
Date: 2014-05-21 21:55:03
From: Mike Tod
Source: smtp-error-calling-using-anonymous

I'm trying to send a message to an internal SMTP server using anonymous.

My understanding is that I should only need to remove the client.Authenticate(SmtpUserID, SmtpPassword); call to send it via anonymous.

I keep getting the following error : Client was not authenticated (530).

Code example:

[code lang='c#']
// Create a new instance of the SmtpClient class.
using (SmtpClient client = new SmtpClient())
{   // Connect to the server.
client.Connect(SmtpServerAddress, SmtpPort);
// test for anonymous login
if (!String.IsNullOrEmpty(SmtpUserID))
client.Authenticate(SmtpUserID, SmtpPassword);
// Create a new mail message.
MailMessage msg = new MailMessage();
msg.Subject = @subjectStr;
msg.Priority = Priority;
msg.BodyText = @bodyStr;
if (fileAttachment != null)
ReportLog(trfid, msgStr, EventLogEntryType.Information, 1000, Actions.Internal);
catch (SmtpException ex)


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