Develop Reference

5.5.1 authentication error required in c#

I have tried most of the tweaks advised but none work.
I have tried :
1.Enabling 2-step verification on gmail
2.Enabled less secured app on gmail
3.Changed password to strong
Earlier I made an account for in gmail and by mistake entered a wrong phone number.But that email workjed fine on my C# application, I was able to send email. But, as I am India and client in US, so had put location as US. So when logged into gmail it logged me out saying some suspicious activity So I had to create a new account.
But since then it gave me an error:
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
heres my code :
SmtpClient client = new SmtpClient(txtsmtp.Text);
c ServicePointManager.ServerCertificateValidationCallback =delegate(object s, X509Certificate certificate,X509Chain chain, SslPolicyErrors sslPolicyErrors)
{
return true;
};
client.UseDefaultCredentials = false;
client.Port = Convert.ToInt16(txtport.Text);
client.Credentials = new System.Net.NetworkCredential(txtuserid.Text, txtpassword.Text);
client.EnableSsl = true;
client.Timeout = 200000;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3 | SecurityProtocolType.Tls;
MailMessage mail = new MailMessage();
mail.To.Add(txtsendto.Text);
mail.From = new MailAddress(cmbuseremailaddress.Text);
mail.Subject = txtsubject.Text;
mail.Body = txtmessage.Text;
mail.Bcc.Add(textBox1.Text);
mail.Priority = MailPriority.High;
try
{
client.Send(mail);
MessageBox.Show("Mail Sent Successfully.");
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
Here port no I am using is 587
So please let me know where and what I am missing.
Thanks

error in sending email by yahoo smtp

i config my outlook 2010 by thie article to send and receive email from yahoo.com it works good without any problem.
i develop a small application to send my emails by my application but it gave me errors:
"unable to read data from the transport connection:an exist connection was
forcibly closed by the remote host."
my codes:
try
{
SmtpClient smtp = new SmtpClient("smtp.mail.yahoo.com", 465);
smtp.UseDefaultCredentials = true;
smtp.EnableSsl = true;
smtp.Credentials = new System.Net.NetworkCredential("myid", "mypass");
smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
MailMessage mailMessage = new MailMessage();
mailMessage.From = new System.Net.Mail.MailAddress("myid#yahoo.com", "blabla");
mailMessage.To.Add(new System.Net.Mail.MailAddress("xxx#live.com", "xxx#live.com"));
mailMessage.Subject = "test";
mailMessage.Body = "test";
mailMessage.IsBodyHtml = false;
mailMessage.SubjectEncoding = System.Text.Encoding.UTF8;
mailMessage.BodyEncoding = System.Text.Encoding.UTF8;
mailMessage.Priority = MailPriority.High;
smtp.Send(mailMessage);
Console.WriteLine("hooooooooooraaaaaaaaaaaaaaa");
Console.ReadKey();
}
catch (Exception err)
{
Console.WriteLine(err.InnerException.Message);
Console.ReadKey();
return;
}

From MSDN
Some SMTP servers require that the client be authenticated before the
server sends e-mail on its behalf. Set this property to true when this
SmtpClient object should, if requested by the server, authenticate
using the default credentials of the currently logged on user. For
client applications, this is the desired behavior in most scenarios.
The UseDefaultCredentials = true sends to the SMTP server the credentials of the current logged in user (i.e. the Windows User) not the credentials you have defined.
Try with UseDefaultCredentials = false

Hmailserver C# SMTP

I'm just trying to get my hmailserver to send mail from my C# program. The part that's killing me is the SSL part.
I originally got this error: The SMTP server requires a secure connection or the client was not authenticated. The server response was: SMTP authentication is required.
So I added: smtp.EnableSsl = true; and now I get Server does not support secure connections.
Here is my code, this is driving me nuts. Do I have to create my own SSL or is there a way to disable SSL on hmailserver side?
MailMessage mail = new MailMessage("jlnt#ademo.net", "com", "NEW Item", emailBody);
SmtpClient smtp = new SmtpClient("1.1.1.250");
smtp.Port = 25;
NetworkCredential login = new NetworkCredential("ja#test.net", "dg");
smtp.Credentials = login;
smtp.EnableSsl = true;
smtp.UseDefaultCredentials = false;
smtp.Send(mail);

Ahh okay what you have to do is in HMailServer go to advanced- ip ranges. Create a new IP range for example if you 192.168.1.2, you have to make the range 192.168.1.1-192.168.1.3, then at bottom uncheck all the required smtp authentication boxes.
Annoying...

To enable secure connection to send email throught your email provider, you have to change the port number.
MailMessage mail = new MailMessage("jlnt#ademo.net", "com", "NEW Item", emailBody);
SmtpClient smtp = new SmtpClient("1.1.1.250");
//smtp.Port =25;
smtp.Port =587;
NetworkCredential login = new NetworkCredential("ja#test.net", "dg");
smtp.Credentials = login;
smtp.EnableSsl = true;
smtp.UseDefaultCredentials = false;
smtp.Send(mail);

i was having this issue, what i did was used localhost ip and EnableSsl to false
SmtpClient smtpClient = new SmtpClient();
smtpClient.Host = "127.0.0.1";
smtpClient.Credentials = new NetworkCredential("test#123test.com", "pass123");
smtpClient.EnableSsl = false;
// then your other statements like: from, to, body, to send mail
this guide will help you setup custom NetworkCredentials in HMailServer as used above, hope helps someone.

I have stumbled on this question when trying to configure hMailServer to work to e-mail sending from C#. I have tried the following:
C# SmtpClient - does not work with implicit SSL - see this question and answers
AegisImplicitMail from here - could not make it work with UTF-8 strings (I have diacritics in my strings)
MailKit from here - very powerful and mature, no problems using it
I aimed for the following:
decent security
being able to send e-mails to mainstream e-mail providers (e.g. Google, Yahoo) and reach Inbox
being able to receive e-mails from mainstream e-mail providers
C# code
public void MailKitSend(string senderEmail, string senderName, string subject, string bodyText, string receivers, string receiversCc)
{
// no receivers, no e-mail is sent
if (string.IsNullOrEmpty(receivers))
return;
var msg = new MimeMessage();
msg.From.Add(new MailboxAddress(Encoding.UTF8, senderName, senderEmail));
msg.Subject = subject;
var bb = new BodyBuilder {HtmlBody = bodyText};
msg.Body = bb.ToMessageBody();
IList<string> receiversEmails = receivers.Split(new[] { ";" }, StringSplitOptions.RemoveEmptyEntries).ToList();
foreach (string receiver in receiversEmails)
msg.To.Add(new MailboxAddress(Encoding.UTF8, "", receiver));
if (!string.IsNullOrEmpty(receiversCc))
{
IList<string> receiversEmailsCc = receiversCc.Split(new[] { ";" }, StringSplitOptions.RemoveEmptyEntries).ToList();
foreach (string receiverCc in receiversEmailsCc)
msg.Cc.Add(new MailboxAddress(Encoding.UTF8, "", receiverCc));
}
try
{
var sc = new MailKit.Net.Smtp.SmtpClient();
if (!string.IsNullOrWhiteSpace(SmtpUser) && !string.IsNullOrWhiteSpace(SmtpPassword))
{
sc.Connect(SmtpServer, 465);
sc.Authenticate(SmtpUser, SmtpPassword);
}
sc.Send(msg);
sc.Disconnect(true);
}
catch (Exception exc)
{
string err = $"Error sending e-mail from {senderEmail} ({senderName}) to {receivers}: {exc}";
throw new ApplicationException(err);
}
}
hMailServer configuration
1) Opened ports - 25, 143, 465, 995 are opened to ensure that you can send and receive e-mail
2) TCP/IP ports configuration
SMTP / 0.0.0.0 / port 25 / no security (allow receiving start process)
SMTP / 0.0.0.0 / port 465 / SSL/TLS security (must define a SSL certificate)
POP3 / 0.0.0.0 / port 995 / SSL/TLS security (use the same SSL certificate)
3) pre C# testing
Run Diagnostics from hMailServer Administrator
Use an e-mail client that allows manual configuration of various settings such as ports for each protocol, security. I have used Thunderbird. Include sending of e-mails to external providers and receiving e-mails from them (I have tried with Gmail).
I made no changes in IP ranges and left the implicit ones (My computer and the Internet).

Although it's 7 years passed since the accepted answer was posted - I also upvoted it in the beginning - I want to emphasize that the suggested solution disables the whole authentication process which is unnecessary. The problem is the line with :
smtp.UseDefaultCredentials = false;
Just remove that line and it should work.
I post here the working solution for me (note that I'm not using SSL):
MailMessage mail = new MailMessage("a1#test.com", "foooo#gmail.com");
SmtpClient client = new SmtpClient();
client.Credentials = new NetworkCredential("a1#test.com", "test");
client.Port = 25;
client.EnableSsl = false;
client.DeliveryMethod = SmtpDeliveryMethod.Network;
client.UseDefaultCredentials = false;
client.Host = "...IPv4 Address from ipconfig...";
mail.Subject = "this is a test email.";
mail.Body = "this is my test email body";
client.Send(mail);

Send mail works locally but not on server?

This code works locally, but when I upload it to my server on Godaddy, it does not send the e-mail. Any idea why it doesn't work on their server? What do I need to change?
try {
MailMessage mail = new MailMessage();
SmtpClient SmtpServer = new SmtpClient("smtp.gmail.com");
mail.From = new MailAddress("Myemail#gmail.com");
mail.To.Add("Myemail#gmail.com");
mail.Subject = "New sign up";
mail.Body = "New member";
SmtpServer.Port = 587;
SmtpServer.Credentials = new System.Net.NetworkCredential("Myemail#gmail.com", "**Mypass**");
SmtpServer.EnableSsl = true;
SmtpServer.Send(mail);
} catch(Exception ex) {
throw ex;
}

They may be blocking outgoing SMTP connections in order to prevent spammers from using their service to send spam. You should check what error messages you're getting and check your server host's policy.

There are a couple of things you need to do when sending from inside a site hosted from Godaddy. Use their relay server to send the message (this won't work from your dev machine, you'll have to test it live after you upload it). Here is the relay server info. Also make sure the "from" address is an email within the same domain. I usually use the same as the toAddress. See here for info on why this is necessary.
This is the code I'm using to send from a site inside Godaddy:
btnSend.Disabled = true;
const string serverHost = "relay-hosting.secureserver.net";
var msg = new MailMessage(toAddress, toAddress);
msg.ReplyTo = new MailAddress(emailFrom);
msg.Subject = subject;
msg.Body = emailBody;
msg.IsBodyHtml = false;
try
{
var smtp = new SmtpClient();
smtp.Host = serverHost;
smtp.Credentials = new System.Net.NetworkCredential("account", "password");
smtp.Send(msg);
}
catch (Exception e)
{
//Log the errors so that we can see them somewhere
}

You need to send your email via the godaddy smtp servers. I experienced the same issue with them before I think. I believe they give instructions of how to login via their FAQ.

If you have ssh access to the server, try to telnet smtp.google.com via 25 and 465 ports also. If you get a timeout, then you're likely firewalled from connecting to these ports outside a certain IP range.
Port 587 is for TLS. As you're using SSL, try port 465.

SmtpDeliveryMethod.PickupDirectoryFromIis strange behavior

I think i need some guru lights!
public void SendEndingMail(string fileName)
{
SmtpClient client;
client = new SmtpClient("smtp.myserver.com", 25);
//client = new SmtpClient();
if (!string.IsNullOrEmpty(""))
{
System.Net.NetworkCredential credential = new NetworkCredential("", "");
client.Credentials = credential;
}
client.UseDefaultCredentials = true;
client.DeliveryMethod = SmtpDeliveryMethod.Network;
//client.DeliveryMethod = SmtpDeliveryMethod.PickupDirectoryFromIis;
MailAddress fromAddress = new MailAddress("mailing#mydom.com", "Elec");
MailAddress toAdrress = new MailAddress("mailing#mydom.com");
using (System.Net.Mail.MailMessage mailMessage = new System.Net.Mail.MailMessage(fromAddress, toAdrress))
{
mailMessage.Attachments.Add(new System.Net.Mail.Attachment(fileName));
mailMessage.IsBodyHtml = false;
mailMessage.BodyEncoding = System.Text.Encoding.UTF8;
try
{
client.Send(mailMessage);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message.ToString());
}
}
}
Is that true that:
when i set
client.DeliveryMethod = SmtpDeliveryMethod.PickupDirectoryFromIis;
It does not matter whichever smtp server i use
client = new SmtpClient("smtp.myserver.com", 25);
//client = new SmtpClient();
The both lines are the same since it will use LOCAL IIS ?!!!
Is this is true, it is not normal that the API is build this way!? it is very confusing...
Thanks
Jonathan

IIRC, when the SmtpClient sends the email, it looks at the .DeliveryMethod value. If the value is Network, then it sends via network. If it is PickupDirectoryFromIis, then it ignores any specified SMTP server (because it just writes and the email to the filesystem), and writes it to the Pickup directory. No network communication takes place.

That is a bug in the Send routine - it creates an smtp server object even if one isn't specified, and when it later (after Send) tries to dispose it, it throws an exception. This happens AFTER the mail is successfully placed in the pickup directory, so the mail will be sent.
Workarounds:
Specify localhost as SMTP server. It won't be used, but prevents the exception.
A blind try/catch around the Send method (BAD solution).