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Mail sending fails through c# when encryption connection is TLS

I am setting up mail sending in my code as below
NetworkCredential nc = new NetworkCredential(ConfigurationManager.AppSettings["EmailId"].ToString(), ConfigurationManager.AppSettings["Password"].ToString());
MailMessage mm = new MailMessage();
mm.From = new MailAddress(SendEmailaddress);
mm.Body = "Test Mail";
mm.IsBodyHtml = true;
mm.BodyEncoding = System.Text.Encoding.UTF8;
mm.To.Add(ToEmailAddress);
mm.Subject = "Test";
SmtpClient sp = new SmtpClient();
sp.UseDefaultCredentials = false;
sp.Credentials = nc;
sp.EnableSsl = true;
sp.DeliveryMethod = SmtpDeliveryMethod.Network;
sp.Port = 587
sp.Host = ConfigurationManager.AppSettings["SMTP"].ToString();
sp.Send(mm);
A error is thrown at the time of mail sending. Mail sending works if I configure outlook on the same PC with these settings with TLS as encrypted connnection.
I have checked many posts where it is suggested that EnableSsl = true should be set for TLS to work but it does not work for me. It throws below error
Transaction failed. The server response was: 5.7.1
: Recipient address rejected: Access denied
at System.Net.Mail.RecipientCommand.CheckResponse(SmtpStatusCode
statusCode, String response) at
System.Net.Mail.SmtpTransport.SendMail(MailAddress sender,
MailAddressCollection recipients, String deliveryNotify,
SmtpFailedRecipientException& exception) at
System.Net.Mail.SmtpClient.Send(MailMessage message)
I have hit a roadblock as no solution is found. is there a setting which needs to be done on server?

protected void SendAlertEmail(string smtpserver, string smtpport, string smtpuser, string smtppass, int ssl, int auth, string subject, string from, string to, string body)
{
try
{
MailMessage mail = new MailMessage();
mail.From = new MailAddress(SplitEmailStrging(from), HttpUtility.HtmlDecode(Request.Form["senderName"]));
string emails = to;
if (emails.Contains(","))
{
string[] emailslist = Regex.Split(emails, #",");
foreach (string email in emailslist)
{
mail.To.Add(SplitEmailStrging(email));
}
}
else
{
if (emails.Contains("<"))
{
mail.To.Add(SplitEmailStrging(emails));
// Response.Write(SplitEmailStrging(emails));
}
else
{
mail.To.Add(emails);
// Response.Write(emails);
}
}
mail.Subject = subject;
mail.IsBodyHtml = true;
mail.Body = HttpUtility.HtmlDecode(body);
SmtpClient client = new SmtpClient(smtpserver);
if (int.Parse(smtpport) == 465)
{
client.Port = 25;
}
else
{
client.Port = int.Parse(smtpport);
}
if (ssl == 1)
{
client.EnableSsl = true;
}
else
{
client.EnableSsl = false;
}
client.DeliveryMethod = SmtpDeliveryMethod.Network;
System.Net.NetworkCredential credentials = new System.Net.NetworkCredential(smtpuser, smtppass);
client.UseDefaultCredentials = false;
client.Credentials = credentials;
client.Send(mail);
}
catch (Exception ex)
{
Response.Write("Error: " + ex.InnerException.Message);
Response.End();
}
}

Time out error while sending mail to gmail account using smtp port 465 in asp.net

public void SendEmailWithAttachment(string pFrom, string pTo, string pSubject, string pBody, string pServer, string strAttachmentPDFFileNames)
{
try
{
System.Net.Mail.MailMessage Message = new System.Net.Mail.MailMessage();
string UserName = ConfigurationManager.AppSettings["SMTPUserName"];
string Password = ConfigurationManager.AppSettings["SMTPPassword"];
if (pTo.Contains(","))
{
string[] ToAdd = pTo.Split(new Char[] { ',' });
for (int i = 0; i < ToAdd.Length; i++)
{
Message.To.Add(ToAdd[i]);
}
}
else
{
Message.To.Add(pTo);
}
//System.Net.Mail.MailAddress toAddress = new System.Net.Mail.MailAddress(pTo);
//Message.To.Add(toAddress);
System.Net.Mail.MailAddress fromAddress = new System.Net.Mail.MailAddress(pFrom);
Message.From = fromAddress;
Message.Subject = pSubject;
Message.Body = pBody;
Message.IsBodyHtml = true;
// Stream streamPDFImages = new MemoryStream(bytPDFImageFile);
//System.Net.Mail.SmtpClient
var smtpClient = new System.Net.Mail.SmtpClient();
{
Message.Attachments.Add(new System.Net.Mail.Attachment(strAttachmentPDFFileNames));
smtpClient.EnableSsl = true;
smtpClient.Host = pServer;
smtpClient.DeliveryMethod = System.Net.Mail.SmtpDeliveryMethod.Network;
smtpClient.Credentials = new System.Net.NetworkCredential(UserName, Password);
smtpClient.Port = 465;
smtpClient.Send(Message);
}
}
catch (Exception Exc)
{
Exception ex = new Exception("Unable to send email . Please Contact administrator", Exc);
throw ex;
}
}

SmtpClient smtp = new SmtpClient("smtp.gmail.com", 587);
smtp.UseDefaultCredentials = false;
smtp.Credentials = new NetworkCredential("yourMail", "yourPassword");
smtp.EnableSsl = true;
MailMessage msg = new MailMessage(sendFrom, "yourMail");
msg.ReplyToList.Add(sendFrom);
msg.Subject = subject;
msg.Body = bodyTxt;
System.Net.Mail.Attachment attachment = new System.Net.Mail.Attachment(#"C:\Projects\EverydayProject\test.txt");
msg.Attachments.Add(attachment);
smtp.Send(msg);
Here is working code to send an email to gmail smtp. From what I see you don't set UseDefaultCredentials = false and you are using wrong port. Also you MUST NOT override exceptions like this., throw the initial exception. Also for this to work you need to turn off security setting in your Gmail account. You can google it.

How send email async in MVC

In my system, I need send lot of emails. But, if I wait to send all the emails, the page gets too slow. I have tried to create an async class - but, the class starts and dies before the emails are even sent.
public class NotificationManager
{
public void SendNotification(NotificationData data)
{
data.MailTo = new WorkflowManager().GetEmailNotification((StatusType)data.Issue.StatusID, data.Issue.IssueId);
Task.Factory.StartNew(() =>
{
new MailManager().SendMessage(data);
});
}
}
class MailManager
{
static ILog log = log4net.LogManager.GetLogger(typeof(MailManager));
public static void SendMessage(Models.Extensions.NotificationData data)
{
var domain = string.Format("{0}/{1}", HttpContext.Current.Request.Url.AbsoluteUri.Replace("Edit", "IssueDetail"), data.Issue.IssueCode);
string type = new TypeManager().GetTypeById(data.Issue.IssueTypeID).Name;
string status = new StatusManager().GetStatusById(data.Issue.IssueTypeID).Name;
var body = string.Format("<h2>[{3}]</h2><br/>{0}<br/><br/><a href='{1}'>Issue</a><br/>[Ticket Number: {2}]",
data.Issue.Description, domain, data.Issue.IssueCode, type);
var subject = string.Format("[{0}] {1}", status, data.Issue.Summary);
SendEmailAwaitable(data.MailTo, subject, body);
log.Error("End Send Email Async");
}
private async Task<bool> SendEmailAwaitable(List<MailAddress> To, string Subject, string Body, bool isBodyHtml = true)
{
Settings s = new Settings();
MailMessage message = new MailMessage();
MailAddress fromAddress = new MailAddress(s.Email, s.EmailDisplayName);
SmtpClient smtpClient = new SmtpClient();
NetworkCredential basicCredential = new NetworkCredential(s.EmailUserName, s.EmailPassword);
string userToken = Subject;
smtpClient.Host = s.EmailServer;
smtpClient.UseDefaultCredentials = false;
smtpClient.Credentials = basicCredential;
message.From = fromAddress;
message.Subject = Subject;
message.IsBodyHtml = isBodyHtml;
message.Body = Body;
foreach (var item in To)
{
userToken += ":To: " + item.Address;
message.To.Add(item);
}
smtpClient.SendCompleted += smtpClient_SendCompleted;
smtpClient.SendAsync(message, null);
await Task.Yield();
return true;
}

Sending an email programmatically through an SMTP server

Trying to send an email through an SMTP server, but I'm getting a nondescript error on the smtp.Send(mail); snippet of code.
Server side, the relay IP addresses look correct. Scratching my head about what I'm missing.
MailMessage mail = new MailMessage();
mail.To.Add(txtEmail.Text);
mail.From = new MailAddress("no-reply#company.us");
mail.Subject = "Thank you for your submission...";
mail.Body = "This is where the body text goes";
mail.IsBodyHtml = false;
SmtpClient smtp = new SmtpClient();
smtp.Host = "mailex.company.us";
smtp.Credentials = new System.Net.NetworkCredential
("AdminName", "************");
smtp.EnableSsl = false;
if (fileuploadResume.HasFile)
{
mail.Attachments.Add(new Attachment(fileuploadResume.PostedFile.InputStream,
fileuploadResume.FileName));
}
smtp.Send(mail);

Try adding smtp.DeliveryMethod = SmtpDeliveryMethod.Network; prior to send.
For reference, here is my standard mail function:
public void sendMail(MailMessage msg)
{
string username = "username"; //email address or domain user for exchange authentication
string password = "password"; //password
SmtpClient mClient = new SmtpClient();
mClient.Host = "mailex.company.us";
mClient.Credentials = new NetworkCredential(username, password);
mClient.DeliveryMethod = SmtpDeliveryMethod.Network;
mClient.Timeout = 100000;
mClient.Send(msg);
}
Typically called something like this:
MailMessage msg = new MailMessage();
msg.From = new MailAddress("fromAddr");
msg.To.Add(anAddr);
if (File.Exists(fullExportPath))
{
Attachment mailAttachment = new Attachment(fullExportPath); //attach
msg.Attachments.Add(mailAttachment);
msg.Subject = "Subj";
msg.IsBodyHtml = true;
msg.BodyEncoding = Encoding.ASCII;
msg.Body = "Body";
sendMail(msg);
}
else
{
//handle missing attachments
}

var client = new SmtpClient("smtp.gmail.com", 587);
Credentials = new NetworkCredential("sendermailadress", "senderpassword"),
EnableSsl = true
client.Send("sender mail adress","receiver mail adress", "subject", "body");
MessageBox.Show("mail sent");

This is Adil's answer formatted for C#:
public static class Email
{
private static string _senderEmailAddress = "sendermailadress";
private static string _senderPassword = "senderpassword";
public static void SendEmail(string receiverEmailAddress, string subject, string body)
{
try
{
var client = new SmtpClient("smtp.gmail.com", 587)
{
Credentials = new NetworkCredential(_senderEmailAddress, _senderPassword),
EnableSsl = true
};
client.Send(_senderEmailAddress, receiverEmailAddress, subject, body);
}
catch (Exception e)
{
Console.WriteLine("Exception sending email." + Environment.NewLine + e);
}
}
}

You didn't specify the port.
smtp.Port = 1111; // whatever port your SMTP server uses
The SMTP has three different "standard" ports: 25, 465 and 587. According to msdn documentation, the default value for the Port property is 25.

How to request operating system to send email in c#?

How to request the operating system to send email with a specific subject, body and attachment? The OS should launch the default email client with the fields pre-loaded?
Specifically what API functions are available in C#.net?

Since you want the outlook to send the email, substitute the port number and host with that of the outlook.
To Open Outlook with pre-loaded fields:
using System.Diagnostics;
// ...
Process.Start(String.Format("mailto:{0}?subject={1}&cc={2}&bcc={3}&body={4}", address, subject, cc, bcc, body))
To send the Email directly :
using System.Net;
using System.Net.Mail;
// ...
var fromAddress = new MailAddress("from#gmail.com", "From Name");
var toAddress = new MailAddress("to#example.com", "To Name");
const string fromPassword = "fromPassword";
const string subject = "Subject";
const string body = "Body";
var smtp = new SmtpClient {
Host = "smtp.gmail.com",
Port = 587,
EnableSsl = true,
DeliveryMethod = SmtpDeliveryMethod.Network,
UseDefaultCredentials = false,
Credentials = new NetworkCredential(fromAddress.Address, fromPassword)
};
using(var message = new MailMessage(fromAddress, toAddress) {
Subject = subject,
Body = body
})
{
smtp.Send(message);
}

This is a simple adapter for system SmtpClient that will simplify yours tests.
public class SmtpClientAdapter : ISmtpClient
{
private bool disposed;
private SmtpClient smtpClient = new SmtpClient();
public SendResult Send(MailMessage message)
{
if (disposed)
{
throw new ObjectDisposedException(GetType().FullName);
}
try
{
smtpClient.Send(message);
return SendResult.Successful;
}
catch (Exception e)
{
return new SendResult(false, e.Message);
}
}
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
protected virtual void Dispose(bool disposing)
{
if (disposed)
{
return;
}
if (disposing)
{
if (smtpClient != null)
{
smtpClient.Dispose();
smtpClient = null;
}
}
disposed = true;
}
}
public class SendResult : SimpleResult
{
public SendResult(bool success, string message)
: base(success, message)
{
}
public static SendResult Successful
{
get
{
return new SendResult(true, string.Empty);
}
}
}
Usage
var emailFrom = new MailAddress(sender);
var emailTo = new MailAddress(recipient);
var mailMessage = new MailMessage(emailFrom, emailTo)
{
Subject = "Subject ",
Body = "Body"
};
using (var client = new SmtpClientAdapter())
{
return client.Send(mailMessage);
}

Here is a simple way to do it,
public void SendEmail(string address, string subject, string message)
{
string email = "yrshaikh.mail#gmail.com";
string password = "put-your-GMAIL-password-here";
var loginInfo = new NetworkCredential(email, password);
var msg = new MailMessage();
var smtpClient = new SmtpClient("smtp.gmail.com", 587);
msg.From = new MailAddress(email);
msg.To.Add(new MailAddress(address));
msg.Subject = subject;
msg.Body = message;
msg.IsBodyHtml = true;
smtpClient.EnableSsl = true;
smtpClient.UseDefaultCredentials = false;
smtpClient.Credentials = loginInfo;
smtpClient.Send(msg);
}
Source : Link

A operating system API function for this isn't avaiable.