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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";

Failed to send an EMail with body contains ip address and port no

I have create function to send an email. This function was work successful on localhost but on server its failed without any exception. I know the problem comes from my Port on IP Address.
The sample body is string body = "<p>Please click here</p>Thank You."
The problem is : between IP Address and Port.
Successful send an email if i remove :.
Do you guys have any ideas?
public void Sent(string sender, string receiver, string subject, string body)
{
using (MailMessage mail = new MailMessage(sender, receiver))
{
using (SmtpClient client = new SmtpClient())
{
client.Port = 25;
client.DeliveryMethod = SmtpDeliveryMethod.Network;
client.UseDefaultCredentials = false;
client.Host = "mail.companyName.com.my";
mail.Subject = subject;
mail.IsBodyHtml = true;
mail.Body = body;
client.Send(mail);
}
}
}

You are doing it right, the code to send the mail is ok (you may want to revise the function name and make the smtp host name configurable, but that is not the point here).
The e-mail delivery fails on a relay, there is no immedieate feedback (no exception) to the client about this kind of failure.
The best bet is the IncreaseScoreWithRedirectToOtherPort property set in Set-HostedContentFilterPolicy in case your mail provider is Office365, or a similar spam filter mechanism in any other mail provider that is encountered down the mail delivery chain.
You can set a reply-to address and hope that the destination server will bounce a delivery failure that gives you more information. Or have the admin of the mail server look up the logs. More information here:
https://serverfault.com/questions/659861/office-365-exchange-online-any-way-to-block-false-url-spam

Try setting the 'mail.Body' to receive a Raw Html message instead of a encoded string, like:
mail.Body = new System.Web.Mvc.HtmlHelper(new System.Web.Mvc.ViewContext(), new System.Web.Mvc.ViewPage()).Raw(body).ToString();
Or put a using System.Web.Mvc at the beginning so it gets shorter and easier to understand:
using System.Web.Mvc
mail.Body = new HtmlHelper(new ViewContext(), new ViewPage()).Raw(body).ToString();

send an email using SMTP without password in C#

I have a web application using ASP.net and C#,in one step it will need
from the user to
send an email to someone with an attachments.
my problem is when the user will send the email i don't want to put their
password every time the user send.
i want to send an email without the password of the sender.
any way to do that using SMTP ?
and this is a sample of my code "not all".
the code is worked correctly when i put my password , but without it ,it
is not work, i need a way to send emails without put the password but
in the same time using smtp protocol.
private void button1_Click(object sender, EventArgs e)
{
string smtpAddress = "smtp.office365.com";
int portNumber = 587;
bool enableSSL = true;
string emailFrom = "my email";
string password = "******";
string emailTo = "receiver mail";
string subject = "Hello";
string body = "Hello, I'm just writing this to say Hi!";
using (MailMessage mail = new MailMessage())
{
mail.From = new MailAddress(emailFrom);
mail.To.Add(emailTo);
mail.Subject = subject;
mail.Body = body;
mail.IsBodyHtml = true;
// Can set to false, if you are sending pure text.
// mail.Attachments.Add(new Attachment("C:\\SomeFile.txt"));
// mail.Attachments.Add(new Attachment("C:\\SomeZip.zip"));
using (SmtpClient smtp = new SmtpClient(smtpAddress,portNumber))
{
smtp.UseDefaultCredentials = true;
smtp.Credentials = new NetworkCredential(emailFrom, password);
smtp.EnableSsl = enableSSL;
smtp.Send(mail);
}
MessageBox.Show("message sent");
}
}

I believe this can be accomplished easily, but with some restrictions.
Have a look at the MSDN article on configuring SMTP in your config file.
If your SMTP server allows it, your email object's from address may not need to be the same as the credentials used to connect to the SMTP server.
So, set the from address of your email object as you already are:
mail.From = new MailAddress(emailFrom);
But, configure your smtp connection one of two ways:
Set your app to run under an account that has permission to access the SMTP server
Include credentials for the SMTP server in your config, like this.
Then, just do something like this:
using (SmtpClient smtp = new SmtpClient())
{
smtp.Send(mail);
}
Let the configuration file handle setting up SMTP for you. This is also great because you don't need to change any of your code if you switch servers.
Just remember to be careful with any sensitive settings in your config file! (AKA, don't check them into a public github repo)

EWS Managed API: how to set From of email?

I'm using EWS Managed API to sending email. Account "account#domain.com" have permissions "Send as" to use "sender#domain.com" mailbox to send messages (from Outlook, it's work fine).
But I try from code - it's not work, in mail i'm read in the field "From" "account#domain.com".
....
EmailMessage message = new EmailMessage(service);
message.Body = txtMessage;
message.Subject = txtSubject;
message.From = txtFrom;
....
message.SendAndSaveCopy();
How to make sending mail on behalf of another user? :)

It's been a while since I fiddled with the same thing, and I concluded that it isn't possible, in spite of having "Send as" rights.
Impersonation is the only way to go with EWS, see MSDN:
ExchangeService service = new ExchangeService();
service.UseDefaultCredentials = true;
service.AutodiscoverUrl("app#domain.com");
// impersonate user e.g. by specifying an SMTP address:
service.ImpersonatedUserId = new ImpersonatedUserId(
ConnectingIdType.SmtpAddress, "user#domain.com");
If impersonation isn't enabled, you'll have to supply the credentials of the user on behalf of whom you want to act. See this MSDN article.
ExchangeService service = new ExchangeService();
service.Credentials = new NetworkCredential("user", "password", "domain");
service.AutodiscoverUrl("user#domain.com");
Alternatively you can simply specify a reply-to address.
EmailMessage mail = new EmailMessage(service);
mail.ReplyTo.Add("user#email.com");
However, "Send as" rights do apply when sending mail using System.Net.Mail, which in many cases will do just fine when just sending e-mails. There are tons of examples illustrating how to do this.
// create new e-mail
MailMessage mail = new MailMessage();
mail.From = new MailAddress("user#domain.com");
mail.To.Add(new MailAdress("recipient#somewhere.com"));
message.Subject = "Subject of e-mail";
message.Body = "Content of e-mail";
// send through SMTP server as specified in the config file
SmtpClient client = new SmtpClient();
client.Send(mail);

i think you should use the Sender property so the your code should look like:
EmailMessage message = new EmailMessage(service);
message.Body = txtMessage;
message.Subject = txtSubject;
message.Sender= txtFrom;
....
message.SendAndSaveCopy();

How to set From Address to any email other gmail in ( Sending Email in .NET Through Gmail )?

In this post Sending Email in .NET Through Gmail we have a code to send email through gmail, in the send mail we find from Field contain gmail account that I used
I use the same code but by changing the From Address to any email I want ans set gmail address in Credentials as bellow
var fromAddress = new MailAddress("AnyEmai#mailserver.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("from#gmail.com", fromPassword)
};
using (var message = new MailMessage(fromAddress, toAddress)
{
Subject = subject,
Body = body
})
{
smtp.Send(message);
}
But in the sent email gmail account still appear in From Address and AnyEmai#mailserver.com not appear ... is there any way to do that ?

It's that way by design. You have to find another way to send outbound emails so that the return address you want shows up (I've been there, there seems to be no way to spoof the from address).

Shall you check this question change sender address when sending mail through gmail in c#
I think it is related to your inquiry.

You can import an email id in your gmail account using Mail Settings >> Accounts and Import options and that can be used for sending the mails, however if you are want to use some random email id everytime to send the mails it is not possible. Gmail will treat that as a spoofing/spam and it will reset the mail address to your original mail id before sending the mail.
using System.Net;
using System.Net.Mail;
public void email_send()
{
MailMessage mail = new MailMessage();
SmtpClient SmtpServer = new SmtpClient("smtp.gmail.com");
mail.From = new MailAddress("from#gmail.com");
mail.To.Add("to#gmail.com");
mail.Subject = "Your Subject";
mail.Body = "Body Content goes here";
System.Net.Mail.Attachment attachment;
attachment = new System.Net.Mail.Attachment("c:/file.txt");
mail.Attachments.Add(attachment);
SmtpServer.Port = 587;
SmtpServer.Credentials = new System.Net.NetworkCredential("from#gmail.com", "mailpassword");
SmtpServer.EnableSsl = true;
SmtpServer.Send(mail);
}
There are many other mail services from which you can achieve the same but not through the gmail. Checkout the blog Send email in .NET through Gmail for sending mail using different properties.

The email address needed to be verified by gmail from the account settings.
Please find my blog post for the same describing it in detail, the steps to be followed:
http://karmic-development.blogspot.in/2013/10/send-email-from-aspnet-using-gmail-as.html
before following all the above steps, you need to authenticate your gmail account to allow access to your application and also the devices. Please check all the steps for account authentication at the following link:
http://karmic-development.blogspot.in/2013/11/allow-account-access-while-sending.html