c# Sending emails with authentication. standard approach not working - c#

I am trying to send an email using the following very standard code. However, I get the error that follow...
MailMessage message = new MailMessage();
message.Sender = new MailAddress("sen#der.com");
message.To.Add("reci#pient.com");
message.Subject = "test subject";
message.Body = "test body";
SmtpClient client = new SmtpClient();
client.Host = "mail.myhost.com";
//client.Port = 587;
NetworkCredential cred = new NetworkCredential();
cred.UserName = "sen#der.com";
cred.Password = "correct password";
cred.Domain = "mail.myhost.com";
client.Credentials = cred;
client.UseDefaultCredentials = false;
client.Send(message);
Mailbox unavailable. The server
response was: No such
user here.
This recipient email address definitely works. To make this account work I had to do some special steps in outlook. Specifically, I had to do change account settings -> more settings -> outgoing server -> my outgoing server requires authentication & use same settings. I am wondering if there is some other strategy.
I think the key here is that my host is Server Intellect and I know that some people on here use them so hopefully someone else has been able to get through this. I did talk to support but they said with coding issues I am on my own :o

try this...
NetworkCredential cred = new NetworkCredential();
cred.UserName = "sen#der.com";
cred.Password = "correct password";
//cred.Domain = "mail.myhost.com";
... you should not need to provide the .Domain unless you are using Kerberos or some other complex authentication.
Edit...
Check out my extended answer. It has an example of how to send an email with authentication. It's also has SSL enabled so you may need to remove that part.

there is no mailbox called sen#der.com on server mail.myhost.com, check that

Related

Gmail SMTP failure using c# SmtpClient

Our application has the possibility to send emails via SmtpClient. One of our customer is trying to do so by using his gmail account and it fails resulting in a timeout. However, from our testing lab it works just fine (with another gmail account).
In the trace i can see that the server is not answering with Certificate, Server Key Exchange, Server Hello Done. And im wondering what can be the cause for this?
I also noticed in the traces, the customer is using TLSv1 so I tried to replicate the error on a Windows7 system but still it works for me.
oSmtp = new SmtpClient(this.host, this.port);
oSmtp.DeliveryMethod = SmtpDeliveryMethod.Network;
oSmtp.EnableSsl = ssl;
NetworkCredential oCredential = new NetworkCredential(this.userName, this.password);
oSmtp.Credentials = oCredential;
oSmtp.SendCompleted += new SendCompletedEventHandler(SendCompletedCallback);
string userState = null;
oSmtp.SendAsync(oMsg, userState);
As far as the code goes, enableSsl is true, the port is 587 and we also instructed our customer to check his gmail account and allow less secure applications.
We will ask the customer for more specific details and try to put more traces in our application, but i would like to know if there is anything that can prevent the server to answer with Certificate,...
Inspecting the traces revealed no significant difference between customers Client Hello and our test Client Hello.
Thanks!
This is a working sample i used few days ago:
string fromAddress = "fromaddress#gmail.com";
var toAddress = new MailAddress("fake#email.com", "To person");
const string fromPassword = "pass";
const string subject = "test";
const string body = "Hey now!!";
using (MailMessage mail = new MailMessage())
{
mail.From = new MailAddress(fromAddress);
mail.To.Add(toAddress);
mail.Subject = subject;
mail.Body = body;
mail.IsBodyHtml = true;
//mail.Attachments.Add(new Attachment("C:\\file.zip"));
using (SmtpClient smtp = new SmtpClient("smtp.gmail.com", 587))
{
smtp.UseDefaultCredentials = false;
smtp.Credentials = new NetworkCredential(fromAddress, fromPassword);
smtp.EnableSsl = true;
smtp.Send(mail);
}
}
also make sure to enable Less secure app access for the gmail you are using to send data:

Can not send email by smtp using G Suit account.

This question might be flagged as a duplicate But it is not. Because the code sends email successfully when using normal gmail account that ends with #gmail.com. The problem only happens when using G suit accounts that are custom and ends with #yourdomainname.com.
I am using this code to send email. My account has two-step verification so I created an app password for verification and use it to send email.
using (var mm = new MailMessage(PrivateSettings.SenderEmail, message.Destination))
{
mm.Subject = message.Subject;
mm.Body = message.Body;
mm.IsBodyHtml = true;
var smtp = new SmtpClient
{
Host = "smtp.gmail.com",
EnableSsl = true
};
var networkCred = new NetworkCredential(PrivateSettings.SenderEmail, PrivateSettings.EmailPassword);
smtp.UseDefaultCredentials = true;
smtp.Credentials = networkCred;
smtp.Port = 587;
smtp.Send(mm);
}
The above code sends email successfully when I use my normal gmail account which is se.natnael.zeleke#gmail.com.
But when I use one of my G Suit account , connect#tatarri.com , to send email it fails and shows this error message.
So my question is; is their additional configuration that should be done for G suit gmail accounts.
Additional Info.
I configured both email accounts to use app password. connect#tatarri.com is also registered as admin in my G suit account.
Both email accounts have their IMAP enabled in settings.
I bought tatarri.com domain name from namecheap.
Thank you.
The line:
smtp.UseDefaultCredentials = true;
Tells the SMTP client to use the default credentials of the currently logged in user. This is what you would use for a client application.
In your case, you want to specify credentials other than the current user's, so set it to false:
smtp.UseDefaultCredentials = false;

Can't send email using SMTP

I'm trying to send an email via .net smtp. I am receiving this message:
The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.1 Client was not authenticated
MailMessage mail = new MailMessage();
SmtpClient SmtpServer = new SmtpClient("server", 587);
SmtpServer.DeliveryMethod = System.Net.Mail.SmtpDeliveryMethod.Network;
SmtpServer.UseDefaultCredentials = false;
SmtpServer.EnableSsl = false;
SmtpServer.Credentials = new System.Net.NetworkCredential("username", "password");
mail.From = new MailAddress(FromMail);
mail.To.Add("emailaddress");
mail.Bcc.Add("emailaddress");
mail.Subject = subject;
mail.Body = body;
mail.IsBodyHtml = true;
SmtpServer.Send(mail);
The issue I believe is that the servers are located in the DMZ...anyone have any insight on how to fix this? If we assign the user with domain admin rights, the emails work...due to security reasons we don't want to go that route.
Issue resolved...the network team didn't have port 587 available...once they added it, emails started working for anonymous sender. I no longer need to use credentials. Thanks to all who replied.

Error sending mail with SmtpClient

I've been struggeling a lot with this now.
I try to send mail with my mvc application using my google apps account. But I keep getting errors. It doesn't matter which settings I use. I tried using both port 465 and 587 with ssl and authentication turned on. With 465 I get Operation Timed Out and with 587 I get this message:
The SMTP server requires a secure connection or the client was not
authenticated. The server response was: 5.5.1 Authentication Required
I tried turning of the firewall with no luck. I have also tried to turn off 2-step authentication but I figured out that it wasn't even turned on.
I hope that you can help me
Regards
Here is the code as requested:
public static void SendMail(MailAddress from, MailAddress to, string subject, string body) {
MailMessage mail = new MailMessage();
mail.From = from;
mail.To.Add(to);
mail.Subject = subject;
mail.Body = body;
SmtpClient client;
if (Settings.Port != null)
client = new SmtpClient(Settings.Host, Int32.Parse(Settings.Port));
else
client = new SmtpClient(Settings.Host);
client.EnableSsl = Settings.UseSSL;
client.Timeout = 50000;
client.DeliveryMethod = SmtpDeliveryMethod.Network;
if (Settings.UseAuthentication) {
client.Credentials = new NetworkCredential(Settings.Username, Settings.Password);
client.UseDefaultCredentials = false;
}
client.Send(mail);
}
I have checked all obvius stuff like username and password (username is formed like user#domain.com). I've also stepped through the code to verify my settings class is working as it should
I found out what the problem was. client.UseDefaultCredentials = false; must go before the credentials is set. Now client.Sendmethod returns without exceptions.

Troubleshooting "Mailbox unavailable. The server response was: Access denied - Invalid HELO name" when sending email with SmtpClient

I have been trying to send an email by C#. I have Googled for various examples and have taken bits and pieces from each and from the standard code which everyone would most probably be using.
string to = "receiver#domain.com";
string from = "sender#domain.com";
string subject = "Hello World!";
string body = "Hello Body!";
MailMessage message = new MailMessage(from, to, subject, body);
SmtpClient client = new SmtpClient("smtp.domain.com");
client.Credentials = new NetworkCredential("test#domain.com", "password");
client.Send(message);
However, I keep getting an error stating
System.Net.Mail.SmtpException: Mailbox
unavailable. The server response was:
Access denied - Invalid HELO name (See
RFC2821 4.1.1.1)
So, what do I do now? Is SmtpClient supposed to be special and only work on specific SMTP servers?
It seems your username/password pair is not authenticating successfully with your SMTP server.
EDIT
I think, I found what's wrong here. I have corrected your version below.
string to = "receiver#domain.com";
//It seems, your mail server demands to use the same email-id in SENDER as with which you're authenticating.
//string from = "sender#domain.com";
string from = "test#domain.com";
string subject = "Hello World!";
string body = "Hello Body!";
MailMessage message = new MailMessage(from, to, subject, body);
SmtpClient client = new SmtpClient("smtp.domain.com");
client.UseDefaultCredentials = false;
client.Credentials = new NetworkCredential("test#domain.com", "password");
client.Send(message);
Have you tried setting your auth credentials in the web.Config?
<system.net>
<mailSettings>
<smtp from="test#foo.com">
<network host="smtpserver1" port="25" userName="username" password="secret" defaultCredentials="true" />
</smtp>
</mailSettings>
</system.net>
and your code behind
MailMessage message = new MailMessage();
message.From = new MailAddress("sender#foo.bar.com");
message.To.Add(new MailAddress("recipient1#foo.bar.com"));
message.To.Add(new MailAddress("recipient2#foo.bar.com"));
message.To.Add(new MailAddress("recipient3#foo.bar.com"));
message.CC.Add(new MailAddress("carboncopy#foo.bar.com"));
message.Subject = "This is my subject";
message.Body = "This is the content";
SmtpClient client = new SmtpClient();
client.Send(message);
Try this:
string to = "receiver#domain.com";
string from = "sender#domain.com";
string subject = "Hello World!";
string body = "Hello Body!";
MailMessage message = new MailMessage(from, to, subject, body);
SmtpClient client = new SmtpClient("smtp.domain.com");
// explicitly declare that you will be providing the credentials:
client.UseDefaultCredentials = false;
// drop the #domain stuff from your user name: (The API already knows the domain
// from the construction of the SmtpClient instance
client.Credentials = new NetworkCredential("test", "password");
client.Send(message);
In my case, it was a wrong port. The configuration provided by the hosting didn't worked both SSL (465) and no SSL (25).
I used MS Outlook to "crack" the configuration, and then copied to my application. It was 587 SSL.
This can happen if you don't set EnableSsl.
client.EnableSsl = true;
If you have a webmail client available and you see a cPanel logo it could be a setting there as well.
We got the exception and asked our hosting company to go into:
"Root WHM > Service Configuration >
Exim Configuration Manager > Basic Editor > ACL Options"
and set the Require RFC-compliant HELO setting to Off.
This worked for us after fixing the next error:
SMTP AUTH is required for message submission on port 587
Source:
https://serverfault.com/a/912351/293367

Categories