Develop Reference

C# SMTP MailMessage receiving error "5.7.57 SMTP; Client was not authenticated to send anonymous mail during MAIL FROM"

The code I currently have is:
public void SendEmail(string to, string cc, string bcc, string subject, string body, string attachmentPath = "", System.Net.Mail.MailPriority emailPriority = MailPriority.Normal, BodyType bodyType = BodyType.HTML)
{
try
{
var client = new System.Net.Mail.SmtpClient();
{
client.Host = "smtp-mail.outlook.com";
client.Port = 587;
client.UseDefaultCredentials = false;
client.EnableSsl = true;
client.DeliveryMethod = System.Net.Mail.SmtpDeliveryMethod.Network;
client.Credentials = new NetworkCredential("[my company email]", "[my password]");
client.Timeout = 600000;
}
MailMessage mail = new MailMessage("[insert my email here]", to);
mail.Subject = subject;
mail.Body = body;
client.Send(mail);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
The email address I'm trying to send to is hosted on Office 365's Outlook. We might have to change the specific address later, but they'd likely be configured the same.
However, whenever I try to run the client.Send(mail); command, I receive the same error. The full text of the error is:
The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.57 SMTP; Client was not authenticated to send anonymous mail during MAIL FROM
I've tried a few different things, like switching the port between 25 and 587, changing the host to Office365's, or toggling UseDefaultCredentials and EnableSssl to true or false. But I always see the same error. Is there something else I'm missing?

I found an example code block elsewhere on this site and replacing everything I had with it made the difference.
The function name and parameters were the same, but here's what I replaced the body of it with.
var _mailServer = new SmtpClient();
_mailServer.UseDefaultCredentials = false;
_mailServer.Credentials = new NetworkCredential("my email", "my password");
_mailServer.Host = "smtp.office365.com";
_mailServer.TargetName = "STARTTLS/smtp.office365.com";
_mailServer.Port = 587;
_mailServer.EnableSsl = true;
var eml = new MailMessage();
eml.Sender = new MailAddress("my email");
eml.From = eml.Sender;
eml.To.Add(new MailAddress(to));
eml.Subject = subject;
eml.IsBodyHtml = (bodyType == BodyType.HTML);
eml.Body = body;
_mailServer.Send(eml);
I don't know for certain but I think that replacing the Host value with the smtp Office 365 link rather than an outlook one, as well as remembering to add a Target Name which I did not have before, both did the trick and solved the authorization issue (I had previously confirmed it wasn't a credentials issue with our tech support).

smtp fails to send mail sometimes in c#

I have gone through some questions on this topic. All the answers relate when sending email fails all the time. In my case, it fails only sometimes with exception message:
The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.57 SMTP; Client was not authenticated to send anonymous mail during MAIL FROM...
If I try second time it works. I'm using the following configuration.
using (MailMessage mail = new MailMessage())
{
mail.From = new MailAddress("emailid", "displayname");
mail.To.Add("TOAddress");
mail.Subject = subject1;
mail.Body = body1;
mail.IsBodyHtml = true;
using (SmtpClient smtp = new SmtpClient("Outlook.office365.com", 587))
{
smtp.UseDefaultCredentials = false;
smtp.Credentials = new NetworkCredential("emailid", "password");
smtp.EnableSsl = true;
smtp.Send(mail);
}
}
checked a similar question here , given solutions not working.

Try this(second answer): Gmail Error :The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required
I used this code to send the email:
MailMessage msg = new MailMessage();
msg.From = new MailAddress("sender#gmail.com");
msg.To.Add("receiver#gmail");
msg.Subject = "Hello";
msg.Body = "Test";
SmtpClient smt = new SmtpClient();
smt.Host = "smtp.gmail.com";
System.Net.NetworkCredential ntcd = new NetworkCredential();
ntcd.UserName = "sender#gmail.com";
ntcd.Password = "senderPassword";
smt.Credentials = ntcd;
smt.EnableSsl = true;
smt.Port = 587;
smt.Send(msg);
Also check if your virus scanner doens't block your email from sending.

Error in Sending Email via a SMTP Client

This may be very trivial for you but i just couldn't figure out why am i getting this error message when i run my code. I looked some of the relative questions on this same website for eg Sending email through Gmail SMTP server with C#
but none of them was helpful. Anyone willing to help please?
using different assemblies are also acceptable. so if anyone got a working solution that would be appreciated.
Error Message = The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required. Learn more at
here is my code
System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage();
message.From = new MailAddress("bob#googlemail.com");
message.To.Add("bob#hotmail.com");
message.Subject = "Hello";
message.Body = "Hello Bob ";
message.DeliveryNotificationOptions = DeliveryNotificationOptions.OnFailure;
SmtpClient smtpClient = new SmtpClient("smtp.gmail.com", 587);
smtpClient.EnableSsl = true;
smtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;
smtpClient.UseDefaultCredentials = false;
smtpClient.Credentials = new NetworkCredential("MyGoogleMailAccount",
"mygooglemailpassword");
smtpClient.Send(message.From.ToString(), message.To.ToString(),
message.Subject, message.Body);

I don't think there's anything wrong with your code other than the e-mail addresses. I used this code to successfully send an e-mail from gmail to my personal account (ran it in LINQPad, actually). Simply replace the 3 string values with valid values for your accounts and you should be good to go:
MailMessage message = new System.Net.Mail.MailMessage();
string fromEmail = "myaddr#gmail.com";
string fromPW = "mypw";
string toEmail = "recipient#receiver.com";
message.From = new MailAddress(fromEmail);
message.To.Add(toEmail);
message.Subject = "Hello";
message.Body = "Hello Bob ";
message.DeliveryNotificationOptions = DeliveryNotificationOptions.OnFailure;
using(SmtpClient smtpClient = new SmtpClient("smtp.gmail.com", 587))
{
smtpClient.EnableSsl = true;
smtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;
smtpClient.UseDefaultCredentials = false;
smtpClient.Credentials = new NetworkCredential(fromEmail, fromPW);
smtpClient.Send(message.From.ToString(), message.To.ToString(),
message.Subject, message.Body);
}

By this post.
MailMessage mail = new MailMessage("you#yourcompany.com", "user#hotmail.com");
SmtpClient client = new SmtpClient();
client.Port = 25;
client.DeliveryMethod = SmtpDeliveryMethod.Network;
client.UseDefaultCredentials = false;
client.Host = "smtp.google.com";
mail.Subject = "this is a test email.";
mail.Body = "this is my test email body";
client.Send(mail);

Send SMTP email testing Microsoft Office 365 in .net

i have a mail account on the Exchange Online service. Now i'm trying to test if i am able to send mails to customers ( on varoius domains and on Microsoft Office 365) through c# application
I tried implementing the below code but i am getting the error
"The remote certificate is invalid according to the validation
procedure."
MailMessage mail = null;
mail = new MailMessage();
string[] strToList = "abc#gmail.com"
foreach (string strID in strToList)
{
if (strID != null)
{
mail.To.Add(new MailAddress(strID));
}
}
mail.From = "demo#onmicrosoft.com";
mail.Subject = "testing"
mail.IsBodyHtml = true;
mail.Body = "mail body";
SmtpClient client = new SmtpClient("smtp.outlook.office365.com");
client.Port = 587;
client.EnableSsl = true;
client.UseDefaultCredentials = false;
NetworkCredential cred = new System.Net.NetworkCredential("demo#onmicrosoft.com", "mypassword");
client.Credentials = cred;
client.Send(mail);
Please advice if i am doing anything wrong.
Thanks a lot in advance.

this works for me ( edited from source )
ThreadPool.QueueUserWorkItem(t =>
{
SmtpClient client = new SmtpClient("smtp.office365.com",587);
client.EnableSsl = true;
client.Credentials = new System.Net.NetworkCredential("xxx#yyy.com", "password");
MailAddress from = new MailAddress("xxx#yyy.com", String.Empty, System.Text.Encoding.UTF8);
MailAddress to = new MailAddress("xxx#yyy.com");
MailMessage message = new MailMessage(from, to);
message.Body = "The message I want to send.";
message.BodyEncoding = System.Text.Encoding.UTF8;
message.Subject = "The subject of the email";
message.SubjectEncoding = System.Text.Encoding.UTF8;
// Set the method that is called back when the send operation ends.
client.SendCompleted += new SendCompletedEventHandler(SendCompletedCallback);
// The userState can be any object that allows your callback
// method to identify this send operation.
// For this example, I am passing the message itself
client.SendAsync(message, message);
});
private static void SendCompletedCallback(object sender, AsyncCompletedEventArgs e)
{
// Get the message we sent
MailMessage msg = (MailMessage)e.UserState;
if (e.Cancelled)
{
// prompt user with "send cancelled" message
}
if (e.Error != null)
{
// prompt user with error message
}
else
{
// prompt user with message sent!
// as we have the message object we can also display who the message
// was sent to etc
}
// finally dispose of the message
if (msg != null)
msg.Dispose();
}

In some cases the TLS authentication may cause problems in using smtp.office365.com as SMTP from c#.
Try the following line before the Send(msg) statement (overriding .TargetName):
client.TargetName = "STARTTLS/smtp.office365.com";
This one works for me

This is also best way to send Mail. I have tried it in my project and working fine.
SmtpClient client = new SmtpClient("smtp.office365.com", 587);
client.EnableSsl = true;
client.Credentials = new System.Net.NetworkCredential("From#mail.com", "sdsd#12345");
MailAddress from = new MailAddress("From Address Ex From#mail.com", String.Empty, System.Text.Encoding.UTF8);
MailAddress to = new MailAddress("From Address Ex To#mail.com");
MailMessage message = new MailMessage(from, to);
message.Body = "This is your body message";
message.BodyEncoding = System.Text.Encoding.UTF8;
message.Subject = "Subject";
message.SubjectEncoding = System.Text.Encoding.UTF8;
client.Send(message);

Try smtp.office365.com instead of smtp.outlook.office365.com

Try to use:
ServicePointManager.ServerCertificateValidationCallback =
(sender, certificate, chain, sslPolicyErrors) => true;
This code will allow you to accept invalid certificates.
As Ori Nachum mention in the comment: this is a very BAD practice, and should only use for testing purposes. It is a security risk!

The Error
The SMTP server requires a secure connection or the client was not
authenticated. The server response was: 5.7.1 Client was not
authenticated
often happens when associated user account password is expired or account is locked. Try set "Never expire user password" in Active Directory, if it does not breach your company password policy :) This happened to me while testing with o365 Exchange Online A/c.

Try setting:
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls;
It will ensure the Service's SecurityPoint is TLS.
Please notice an answer here offered setting
ServicePointManager.ServerCertificateValidationCallback =
(sender, certificate, chain, sslPolicyErrors) => true;
May be good for testing purposes - but it's a major security risk!
Do not use with a prod account or in prod environment.

var Client = new SmtpClient("smtp.office365.com", 587);
Client.EnableSsl = true;
Client.Credentials = new System.Net.NetworkCredential("mail", "pass");
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls;
I successfully send mail with code

Time out Error in send mail

I use this code to try and send an email. After a few seconds, it shows me an error message claiming the operation has timed out. How can I resolve this issue?
try
{
MailAddress from = new MailAddress("from#yahoo.com", "name", Encoding.UTF8);
MailAddress to = new MailAddress("to#yahoo.com");
MailMessage message = new MailMessage(from, to);
message.Subject = "Test";
message.SubjectEncoding = Encoding.UTF8;
message.Body = "Test";
message.BodyEncoding = Encoding.UTF8;
SmtpClient client = new SmtpClient();
client.Host = "smtp.mail.yahoo.com";
client.Port = 465;
client.EnableSsl = true;
client.Credentials = new NetworkCredential("example#yahoo.com", "Password");
client.Send(message);
MessageBox.Show("sending Successfully!!!");
}
catch (SmtpException ex)
{
MessageBox.Show(ex.ToString());
}

Are you sure that you can reach smtp.mail.yahoo.com on port 465? Sounds pretty much like a network related issue. Generally when something times out, it means that it tries to connect to the server for a certain amount of time and them stops and gives you an error.
One easy way to test this is to telnet to smtp.mail.yahoo.com on port 465 and see if it times out. You can use Putty or the built in telnet-client in windows, if you have it installed.

As per my understanding, your code won't work because yahoo.com does not provide you access via SMTP. For that you need to upgrade to Yahoo! Mail Plus.
Couldn't find any sort of kb from Yahoo! on this. I got the information from a Yahoo! article on How to read Yahoo! Mail Plus using Outlook Express. The first two lines of the article are very relevant.
Do you want to read and send your Yahoo! email with Outlook Express?
If you are a Yahoo! Mail Plus user you can.
And also, the outgoing SMTP server should be
client.Host = "plus.smtp.mail.yahoo.com";

i had the same problem
you have to set the clietn.port as 25 and you have to specify your login an password in client.Credentials = new NetworkCredential(login,password)
when i did that i can send mail without problem
there is the code
{
SmtpClient client = new SmtpClient("188.125.69.59");//you can put the ip adress or the dns of smtp server (smtp.mail.yahoo.com as exemple)
// Specify the e-mail sender.
// Create a mailing address that includes a UTF8 character
// in the display name.
MailAddress from = new MailAddress("from#yahoo.fr");
// Set destinations for the e-mail message.
MailAddress to = new MailAddress("to#gmail.com");
// Specify the message content.
MailMessage message = new MailMessage(from, to);
message.Body = "This is a test e-mail message sent by an application. ";
// Include some non-ASCII characters in body and subject.
string someArrows = new string(new char[] {'\u2190', '\u2191', '\u2192', '\u2193'});
message.Body ="cc";
message.BodyEncoding = System.Text.Encoding.UTF8;
message.Subject = "test message 1";
message.SubjectEncoding = System.Text.Encoding.UTF8;
string userState = "test message1";
MessageBox.Show("sending");
client.Port = 25;
// client.Timeout = 40000;
client.ServicePoint.MaxIdleTime = 1;
client.Credentials = new System.Net.NetworkCredential("from#yahoo.fr", "pass");
//client.SendAsync(message, userState);
client.Send(message);
MessageBox.Show("Sending message... press c to cancel mail. Press any other key to exit.");
string answer = Console.ReadLine();
// If the user canceled the send, and mail hasn't been sent yet,
// then cancel the pending operation.
// if (answer.StartsWith("c") && mailSent == false)
//{
// client.SendAsyncCancel();
//}
// Clean up.
message.Dispose();
MessageBox.Show("Goodbye.");
}

Use following setting for domain #yahoo.co.in.
var smtp = new System.Net.Mail.SmtpClient();
{
smtp.Host ="smtp.mail.yahoo.co.in";
smtp.Port = 25;
smtp.EnableSsl = true;
smtp.DeliveryMethod = System.Net.Mail.SmtpDeliveryMethod.Network;
smtp.Credentials = new NetworkCredential(fromAddress, fromPassword);
smtp.Timeout = 20000;
}