Develop Reference

How to send email from a C# program

I would like to add email functionality to a WinForm program I'm writing in C#. I have an Android app that has email functionality. What it does is set up the email but then lets the user choose the email program, etc. Once that is chosen the email body is completed. But it's up to the use to select what email app they want to use.
I would like to do the same in Windows but I don't see how. I have tried the following (based on other questions and responses here) :
_from = new MailAddress("my email address", "xxxx");
_to = new MailAddress("xxxx3333#gmail.com", "yyyy");
SmtpClient smtp = new SmtpClient("smtp.gmail.com");
smtp.UseDefaultCredentials = true;
smtp.Port = 587;
smtp.EnableSsl = true;
smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
smtp msgMail = new MailMessage();
smtp.Body = text;
msgMail.Subject = "Subject";
msgMail.From = _from;
msgMail.To.Add(_to);
smtp.EnableSsl = true;
msgMail.Subject = _subject;
msgMail.Body = Text;
msgMail.IsBodyHtml = false;
try
{
mailClient.Send(msgMail);
}
catch (Exception ex)
{
string msg = "Exception caught in sending the email: " + ex.ToString();
showMessage(msg);
}
msgMail.Dispose();
But I get:
The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required.
With similar code in Android, my program just gets to an email form but lets the user decide what email add they will use.
Is there a way to do this in Windows?
There is an almost identical question and response here:
C# Windows Form Application - Send email using gmail smtp
And I think I've followed this but...doesn't work.

To directly answer your question - you probably haven't enabled less secure apps on the gmail account you are using.
Otherwise though, you could investigate the syntax of mailto if you want to let the user elect a mail client to use to send the email: https://www.labnol.org/internet/email/learn-mailto-syntax/6748/
From the link:
Send an email to Barack Obama with the subject “Congrats Obama” and some text in the body of the email message
<a href=”mailto:obama#whitehouse.gov?
subject=Congrats%20Obama&body=Enjoy%20your%20stay%0ARegards%20″>
This isn't directly related to C#/Windows - but I do know entering mailto:someone#somewhere.com at the Run prompt works:
Presumably then you could do something like: (untested)
Process.Run("mailto:someone#somewhere.com");

From the server response messages it looks like you have to provide login credentials before you are allowed to send.
Replace:
smtp.UseDefaultCredentials = true;
With:
smtp.Credentials = new System.Net.NetworkCredential("yourusername", "yourpassword");
This should do the trick.

You may have forgotten in your code to add the Host
Try to use this :
SmtpClient smtp = new SmtpClient();
smtp.UseDefaultCredentials = true;
smtp.Host = "SRVMAIL";

`The operation has timed out.` exception when sending mail using ZOHO SMTP configuration

I am using ZOHO mail server for sending mails through my application. But its unable to connect to server and throws exception The operation has timed out.. Following is my code:
public int sendMail(string from, string to, string subject, string messageBody) {
try {
SmtpClient client = new SmtpClient();
client.Port = 465;
client.Host = "smtp.zoho.com";
client.EnableSsl = true;
client.Timeout = 10000;
client.DeliveryMethod = SmtpDeliveryMethod.Network;
client.UseDefaultCredentials = false;
client.Credentials = new System.Net.NetworkCredential(Username, Password);
MailMessage mm = new MailMessage(from, to, subject, messageBody);
mm.BodyEncoding = UTF8Encoding.UTF8;
mm.IsBodyHtml = true;
mm.DeliveryNotificationOptions = DeliveryNotificationOptions.OnFailure;
client.Send(mm);
return 0;
} catch (Exception) {
throw;
}
}
I also tried using port 587 as suggested here Send email using smtp but operation timed out using ZOHO. But still problem persists.
Zoho SMTP Configuration help link: https://www.zoho.com/mail/help/zoho-smtp.html

Time out problems are usually related to network, ports problems, I haven't experience sending emails using SSL or TLS methods but I'd check this too, of course I suppouse you changed the port number when you say you tried TLS.

After trying all kinds of firewall/anti-virus/router port forwarding, port scanners, website port checkers I simply found out that with code almost identical to yours I was able to send mail successfully!
All you need to do is change smtp to:
smtp.zoho.eu
and port to:
587

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);

How to send HTML email with Image using asp.net with c#

Hi all of you I try following code to send HTML email along with Image in HTML
but I can receive only text format mail not Image
public void HTML_mail(string mailTo,string mailSub,string mailMessage)
{
try
{
SmtpClient client = new SmtpClient();
client.DeliveryMethod = SmtpDeliveryMethod.Network;
client.EnableSsl = true;
//client.Host = "smtp.gmail.com";
//client.Port = 587;
//WITH SMTP Server with Authenticaton
client.Host = mailServer;
client.Port = Convert.ToInt16(serverPort);
// setup Smtp authentication
System.Net.NetworkCredential credentials =
new System.Net.NetworkCredential(userName, passWord);
client.UseDefaultCredentials = false;
client.Credentials = credentials;
MailMessage msg = new MailMessage();
msg.From = new MailAddress(userName);
msg.To.Add(new MailAddress(mailTo));
msg.Subject = mailSub;
msg.IsBodyHtml = true;
msg.Body = string.Format(mailMessage);
//HTML CODE "<html><head></head><body><p><h3>Dadu</h3></p><img src='http://localhost:2727/photo/mukeshwedsjashmin/1/Suresh2.jpg' height='500px' width='500px' alt='' /></body>"
try
{
client.Send(msg);
//lblMsg.Text = "Your message has been successfully sent.";
}
catch (Exception ex)
{
//lblMsg.ForeColor = Color.Red;
//lblMsg.Text = "Error occured while sending your message." + ex.Message;
}
}
catch(Exception ex)
{
}
}
I can Only see the "Dadu" in the mail
I choose display Image on my gmail A/C

You're email is referencing a localhost image, try it wih an online one as the image may not be available to the email.

Your email is referencing a local image:
http://localhost:2727/photo/mukeshwedsjashmin/1/Suresh2.jpg
The only e-mail receiver that will be able to see that image is yourself. No one else will have access to your local web server, thus won't be able to see the image.
You need to reference an image that is available to the public.
As a side note
In my experience, sending emails like this from a local mail server, especially if the email contain HTML and images, will almost certainly be caught as spam. I prefer to send my emails through an email delivery service. I only have experience with Postmark, which has a good .Net library, but I bet there are other great services as well.

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.