System.Security.Cryptography.CryptographicException: The handle is invalid - c#

I am getting exception while sending mail through C# for
SmtpClient client = new SmtpClient()
as System.Security.Cryptography.CryptographicException: The handle is invalid.
MailMessage mail = new MailMessage(from,to);
mail.To.Add(to);
mail.From = new MailAddress(from, "", System.Text.Encoding.UTF8);
mail.Subject = "This is a test mail";
mail.SubjectEncoding = System.Text.Encoding.UTF8;
mail.Body = fr.message;
mail.BodyEncoding = System.Text.Encoding.UTF8;
mail.IsBodyHtml = true;
mail.Priority = MailPriority.High;
SmtpClient client = new SmtpClient();
//Add the Creddentials- use your own email id and password
client.Credentials = new System.Net.NetworkCredential(from, Password);
client.Port = 587; // Gmail works on this port
client.Host = "smtp.gmail.com";
client.EnableSsl = true; //Gmail works on Server Secured Layer
client.Send(mail);
I am not getting why this happens?

Check your project settings and make sure you have checked NTLM Authentication:

Related

How to fix unstable smtp mail service?

I have an ASP.NET Core 3.1 Web API project. I am using Entity Framework.
When I pass data statically to a smtp client, mail is sent and there is no problem:
SmtpClient smtp = new SmtpClient();
smtp.UseDefaultCredentials = false;
smtp.Credentials = new System.Net.NetworkCredential("development#mail.com.tr", "password");
smtp.Port = 587;
smtp.Host = "mail.com.tr";
smtp.EnableSsl = false;
MailMessage mail = new MailMessage();
mail.To.Add("atakan#mail.com.tr");
mail.From = new MailAddress("development#mail.com.tr");
mail.Subject = PostaSubject;
mail.IsBodyHtml = true;
mail.Body = MailTemplate(subject, subject);
smtp.Send(mail);
But when I get the smtp client data from the data in the context, sometimes the mail is sent, sometimes it cannot be thrown and it works unstable. How can I fix it?
SmtpClient smtp = new SmtpClient();
smtp.UseDefaultCredentials = false;
smtp.Credentials = new System.Net.NetworkCredential(_context.MailConfigs.Select(x => x.UserName).FirstOrDefault(), _context.MailConfigs.Select(x => x.UserPassword).FirstOrDefault());
smtp.Port = (int)_context.MailConfigs.Select(x => x.SmtpPort).FirstOrDefault();
smtp.Host = _context.MailConfigs.Select(x => x.SmtpHost).FirstOrDefault();
smtp.EnableSsl = false;
MailMessage mail = new MailMessage();
mail.To.Add(_context.MailConfigs.Select(x => x.Reciever).FirstOrDefault());
mail.From = new MailAddress(_context.MailConfigs.Select(x => x.UserName).FirstOrDefault());
mail.Subject = PostaSubject;
mail.IsBodyHtml = true;
mail.Body = MailTemplate(subject, subject);
smtp.Send(mail);
FirstOrDefault will return a value or null, why not use a string variable to capture the value of FirstOrDefault result and if it is not null then send the email or if the value is null then just ignore or write to a log.

The server response was: 5.7.3 Requested action aborted; user not authenticated

I want to send emails using C# for an MVC project and hotmail, I have tried port 25 and 587, using my own credentials, but every time I get '5.7.3 user not authenticated', if I change SSL to false, then I get '5.7.0, Must issue a STARTTLS command first'.
There are 2 other questions with the same problem but one of the answers is old (points me to a setting that doesn't exist in outlook.com) and the other one didn't solve it (changing ssl to false).
This is my code (of course I removed my email and password), question is, what else can I do to get ride of the 5.7.3, am I missing something?
MailMessage mail = new MailMessage(<email>, <email>);
SmtpClient client = new SmtpClient("smtp-mail.outlook.com");
client.Port = 587;
client.DeliveryMethod = SmtpDeliveryMethod.Network;
client.UseDefaultCredentials = false;
client.Credentials = new System.Net.NetworkCredential(<email>, <pass>);
mail.Subject = "this is a test email.";
mail.Body = "this is my test email body";
client.EnableSsl = true;
client.Send(mail);
This code Works normally on my computer!
There are two issues that you should look at:
If you enabled the use of external applications in hotmail
Check the https://account.microsoft.com/account link if your computer
is locked.
My code:
MailMessage mail = new MailMessage("from", "to");
SmtpClient client = new SmtpClient();
client.EnableSsl = true;
client.Host = "smtp-mail.outlook.com";
client.UseDefaultCredentials = false;
client.Credentials = new System.Net.NetworkCredential("email", "password");
client.Port = 587;
client.DeliveryMethod = SmtpDeliveryMethod.Network;
mail.Subject = "test";
mail.Body = "test";
client.Send(mail);

Sending a gmail email

I am trying to send an email through and C# application (Console). Actually I would like it to send an email to any type of email but for the time being if I can get it to send to a gmail account I would be happy enough.
I just want to be able to get this to send to a gmail account for the time being?
Whole Program:
namespace EmailAddress
{
class Program
{
static void Main(string[] args)
{
Program test = new Program();
test.email_send();
}
public void email_send()
{
MailMessage mail = new MailMessage();
SmtpClient SmtpServer = new SmtpClient("smtp.gmail.com");
mail.From = new MailAddress("hg#gmail.com");
mail.To.Add("hg#gmail.com");
mail.Subject = "Test Mail - 1";
mail.Body = "Your attachment is accessible on your computer!";
System.Net.Mail.Attachment attachment;
attachment = new System.Net.Mail.Attachment("g:/example1.txt");
mail.Attachments.Add(attachment);
SmtpServer.Port = 587;
SmtpServer.Credentials = new System.Net.NetworkCredential("your mail#gmail.com", "your password");
SmtpServer.EnableSsl = true;
SmtpServer.Send(mail);
}
}
}
New code: Doesn't hang but will not send the message to the inbox
static void Main(string[] args)
{
Program test = new Program();
//test.email_send();
test.CreateTestMessage4();
}
public void email_send()
{
MailMessage mail = new MailMessage();
SmtpClient smtp = new SmtpClient("smtp.gmail.com");
mail.From = new MailAddress("g#gmail.com");
mail.To.Add("g#gmail.com");
mail.Subject = "Test Mail - 1";
mail.Body = "Your attachment is accessible on your computer!";
System.Net.Mail.Attachment attachment;
attachment = new System.Net.Mail.Attachment("g:\\example1.txt");
mail.Attachments.Add(attachment);//list of attachements
smtp.Port = 587;//google standard -- most of the time wouldn't not set
smtp.EnableSsl = true;
smtp.UseDefaultCredentials = true;
smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
smtp.Credentials = new System.Net.NetworkCredential("*","*");
smtp.Send(mail);
Console.WriteLine("-- Sending Email --");
Console.ReadLine();
}
Can someone try this code and see if it works. For some reason this isn't working so I would like to have someone's fresh perspective of this. I just call this in the main method for an instance of the class.
public void email_send()
{
MailMessage mail = new MailMessage();
SmtpClient smtp = new SmtpClient("smtp.gmail.com");
mail.From = new MailAddress("your email address");
mail.To.Add("your email address");
mail.Subject = "Test Mail - 1";
mail.Body = "Your attachment is accessible on your computer!";
System.Net.Mail.Attachment attachment;
attachment = new System.Net.Mail.Attachment("g:\\example1.txt");
mail.Attachments.Add(attachment);//list of attachements
//smtp.Port = 587;//google standard -- most of the time wouldn't not set
//smtp.EnableSsl = true;
//smtp.UseDefaultCredentials = true;
//smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
//smtp.Credentials = new System.Net.NetworkCredential("your address",
"your password");
smtp.Port = 587;
smtp.Host = "smtp.gmail.com";
smtp.UseDefaultCredentials = false;
smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
smtp.EnableSsl = true;
smtp.Credentials = new System.Net.NetworkCredential("*", "*"); smtp.Send(mail);
Console.WriteLine("-- Sending Email --");
Console.ReadLine();
}
Your code is close:
MailMessage mail = new MailMessage();
using (SmtpClient smtp = new SmtpClient("smtp.gmail.com")) {
mail.From = new MailAddress("haufdoug#gmail.com");
mail.To.Add("haufdoug#gmail.com");
mail.Subject = "Test Mail - 1";
mail.Body = "Your attachment is accessible on your computer!";
System.Net.Mail.Attachment attachment;
attachment = new System.Net.Mail.Attachment("g:\\example1.txt");
mail.Attachments.Add(attachment);
smtp.Port = 587;
smtp.EnableSsl = true;
smtp.UseDefaultCredentials = false;
smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
smtp.Credentials = new System.Net.NetworkCredential("your mail#gmail.com", "your password");
smtp.Send(mail);
}
Now, regarding some of your other questions.
Port 587 is used by Google only. Typically the mail server you connect to will tell you what port to use for SMTP mail; Google said there's is 587.
For sending through other servers you typically won't set the port number.
side notes:
SmtpClient implements the IDisposable interface. So it should be wrapped in a using clause to ensure it is properly disposed of when complete. Unless you are using the .SendAsync() method.
I changed the variable name from SmtpServer to smtp for two reasons. First, naming convention. Variables inside a method are recommended to be camel case (forExampleThis). Second, SmtpServer is a misnomer as the object is an SmtpClient. Those are very different things and it's just bad practice to misname things.
Can you try this, it's working for me:
SmtpClient SmtpServer = new SmtpClient();
SmtpServer.Port = 587;
SmtpServer.Host = smtp.gmail.com;
SmtpServer.UseDefaultCredentials = false;
SmtpServer.DeliveryMethod = SmtpDeliveryMethod.Network;
SmtpServer.EnableSsl = true;
SmtpServer.Credentials = new System.Net.NetworkCredential("your mail#gmail.com", "your password");

Error in Sending Email via a SMTP Client

This may be very trivial for you but i just couldn't figure out why am i getting this error message when i run my code. I looked some of the relative questions on this same website for eg Sending email through Gmail SMTP server with C#
but none of them was helpful. Anyone willing to help please?
using different assemblies are also acceptable. so if anyone got a working solution that would be appreciated.
Error Message = 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
here is my code
System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage();
message.From = new MailAddress("bob#googlemail.com");
message.To.Add("bob#hotmail.com");
message.Subject = "Hello";
message.Body = "Hello Bob ";
message.DeliveryNotificationOptions = DeliveryNotificationOptions.OnFailure;
SmtpClient smtpClient = new SmtpClient("smtp.gmail.com", 587);
smtpClient.EnableSsl = true;
smtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;
smtpClient.UseDefaultCredentials = false;
smtpClient.Credentials = new NetworkCredential("MyGoogleMailAccount",
"mygooglemailpassword");
smtpClient.Send(message.From.ToString(), message.To.ToString(),
message.Subject, message.Body);
I don't think there's anything wrong with your code other than the e-mail addresses. I used this code to successfully send an e-mail from gmail to my personal account (ran it in LINQPad, actually). Simply replace the 3 string values with valid values for your accounts and you should be good to go:
MailMessage message = new System.Net.Mail.MailMessage();
string fromEmail = "myaddr#gmail.com";
string fromPW = "mypw";
string toEmail = "recipient#receiver.com";
message.From = new MailAddress(fromEmail);
message.To.Add(toEmail);
message.Subject = "Hello";
message.Body = "Hello Bob ";
message.DeliveryNotificationOptions = DeliveryNotificationOptions.OnFailure;
using(SmtpClient smtpClient = new SmtpClient("smtp.gmail.com", 587))
{
smtpClient.EnableSsl = true;
smtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;
smtpClient.UseDefaultCredentials = false;
smtpClient.Credentials = new NetworkCredential(fromEmail, fromPW);
smtpClient.Send(message.From.ToString(), message.To.ToString(),
message.Subject, message.Body);
}
By this post.
MailMessage mail = new MailMessage("you#yourcompany.com", "user#hotmail.com");
SmtpClient client = new SmtpClient();
client.Port = 25;
client.DeliveryMethod = SmtpDeliveryMethod.Network;
client.UseDefaultCredentials = false;
client.Host = "smtp.google.com";
mail.Subject = "this is a test email.";
mail.Body = "this is my test email body";
client.Send(mail);

Send email using System.Net.Mail through gmail

I want to send a email through gmail server. I have put the following code but it is getting stuck while sending. Any idea please....
MailMessage mail = new MailMessage();
mail.From = new System.Net.Mail.MailAddress("apps#xxxx.com");
//create instance of smtpclient
SmtpClient smtp = new SmtpClient();
smtp.Port = 465;
smtp.UseDefaultCredentials = true;
smtp.Host = "smtp.gmail.com";
smtp.EnableSsl = true;
//recipient address
mail.To.Add(new MailAddress("yyyy#xxxx.com"));
//Formatted mail body
mail.IsBodyHtml = true;
string st = "Test";
mail.Body = st;
smtp.Send(mail);
The xxxx.com is a mail domain in Google apps.
Thanks...
MailMessage mail = new MailMessage();
mail.From = new System.Net.Mail.MailAddress("apps#xxxx.com");
// The important part -- configuring the SMTP client
SmtpClient smtp = new SmtpClient();
smtp.Port = 587; // [1] You can try with 465 also, I always used 587 and got success
smtp.EnableSsl = true;
smtp.DeliveryMethod = SmtpDeliveryMethod.Network; // [2] Added this
smtp.UseDefaultCredentials = false; // [3] Changed this
smtp.Credentials = new NetworkCredential(mail.From, "password_here"); // [4] Added this. Note, first parameter is NOT string.
smtp.Host = "smtp.gmail.com";
//recipient address
mail.To.Add(new MailAddress("yyyy#xxxx.com"));
//Formatted mail body
mail.IsBodyHtml = true;
string st = "Test";
mail.Body = st;
smtp.Send(mail);
I tried the above C# code to send mail from Gmail to my Corporate ID. While executing the application the control stopped indefinitely at the statement smtp.Send(mail);
While Googling, I came across a similar code, that worked for me. I am posting that code here.
class GMail
{
public void SendMail()
{
string pGmailEmail = "fromAddress#gmail.com";
string pGmailPassword = "GmailPassword";
string pTo = "ToAddress"; //abc#domain.com
string pSubject = "Test From Gmail";
string pBody = "Body"; //Body
MailFormat pFormat = MailFormat.Text; //Text Message
string pAttachmentPath = string.Empty; //No Attachments
System.Web.Mail.MailMessage myMail = new System.Web.Mail.MailMessage();
myMail.Fields.Add
("http://schemas.microsoft.com/cdo/configuration/smtpserver",
"smtp.gmail.com");
myMail.Fields.Add
("http://schemas.microsoft.com/cdo/configuration/smtpserverport",
"465");
myMail.Fields.Add
("http://schemas.microsoft.com/cdo/configuration/sendusing",
"2");
//sendusing: cdoSendUsingPort, value 2, for sending the message using
//the network.
//smtpauthenticate: Specifies the mechanism used when authenticating
//to an SMTP
//service over the network. Possible values are:
//- cdoAnonymous, value 0. Do not authenticate.
//- cdoBasic, value 1. Use basic clear-text authentication.
//When using this option you have to provide the user name and password
//through the sendusername and sendpassword fields.
//- cdoNTLM, value 2. The current process security context is used to
// authenticate with the service.
myMail.Fields.Add
("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate", "1");
//Use 0 for anonymous
myMail.Fields.Add
("http://schemas.microsoft.com/cdo/configuration/sendusername",
pGmailEmail);
myMail.Fields.Add
("http://schemas.microsoft.com/cdo/configuration/sendpassword",
pGmailPassword);
myMail.Fields.Add
("http://schemas.microsoft.com/cdo/configuration/smtpusessl",
"true");
myMail.From = pGmailEmail;
myMail.To = pTo;
myMail.Subject = pSubject;
myMail.BodyFormat = pFormat;
myMail.Body = pBody;
if (pAttachmentPath.Trim() != "")
{
MailAttachment MyAttachment =
new MailAttachment(pAttachmentPath);
myMail.Attachments.Add(MyAttachment);
myMail.Priority = System.Web.Mail.MailPriority.High;
}
SmtpMail.SmtpServer = "smtp.gmail.com:465";
SmtpMail.Send(myMail);
}
}
Set
smtp.UseDefaultCredentials = false
and use
smtp.Credentials = new NetworkCredential(gMailAccount, password);
This have worked for me:
MailMessage message = new MailMessage("myemail#gmail.com", toemail, subjectEmail, comments);
message.IsBodyHtml = true;
try {
SmtpClient client = new SmtpClient("smtp.gmail.com", 587);
client.Timeout = 2000;
client.EnableSsl = true;
client.DeliveryMethod = SmtpDeliveryMethod.Network;
//client.Credentials = CredentialCache.DefaultNetworkCredentials;
client.UseDefaultCredentials = false;
client.Credentials = new System.Net.NetworkCredential("myemail#gmail.com", "mypassord");
client.Send(message);
message.Dispose();
client.Dispose();
}
catch (Exception ex) {
Debug.WriteLine(ex.Message);
}
BUT (as of the time of this writing - Oct 2017)
You need to ENABLE "Allow less secure apps" inside the option "apps with account access" at the "My account" google security/privacy settings (https://myaccount.google.com)
I realise this is an answer to a very old question, with lots of other good answers. I am posting this code to include some of the useful comments posted by other users such as Using Statements and newer methods where some answers have obsolete methods. This code was tested and working as of 11 July 2018.
If sending via your GMail Account ensure that Allow less secure apps is enabled from your control panel
Class Code C#:
public class Email
{
public void NewHeadlessEmail(string fromEmail, string password, string toAddress, string subject, string body)
{
using (System.Net.Mail.MailMessage myMail = new System.Net.Mail.MailMessage())
{
myMail.From = new MailAddress(fromEmail);
myMail.To.Add(toAddress);
myMail.Subject = subject;
myMail.IsBodyHtml = true;
myMail.Body = body;
using (System.Net.Mail.SmtpClient s = new System.Net.Mail.SmtpClient("smtp.gmail.com", 587))
{
s.DeliveryMethod = SmtpDeliveryMethod.Network;
s.UseDefaultCredentials = false;
s.Credentials = new System.Net.NetworkCredential(myMail.From.ToString(), password);
s.EnableSsl = true;
s.Send(myMail);
}
}
}
}
Class Code VB:
Public Class Email
Sub NewHeadlessEmail(fromEmail As String, password As String, toAddress As String, subject As String, body As String)
Using myMail As System.Net.Mail.MailMessage = New System.Net.Mail.MailMessage()
myMail.From = New MailAddress(fromEmail)
myMail.To.Add(toAddress)
myMail.Subject = subject
myMail.IsBodyHtml = True
myMail.Body = body
Using s As New Net.Mail.SmtpClient("smtp.gmail.com", 587)
s.DeliveryMethod = SmtpDeliveryMethod.Network
s.UseDefaultCredentials = False
s.Credentials = New Net.NetworkCredential(myMail.From.ToString(), password)
s.EnableSsl = True
s.Send(myMail)
End Using
End Using
End Sub
End Class
Usage C#:
{
Email em = new Email();
em.NewHeadlessEmail("myemail#gmail.com", "password", "recipient#email.com", "Subject Text", "Body Text");
}
Usage VB:
Dim em As New Email
em.NewHeadlessEmail("myemail#gmail.com", "password", "recipient#email.com", "Subject Text", "Body Text")
Use Port number 587
With the following code, it will work successfully.
MailMessage mail = new MailMessage();
mail.From = new MailAddress("abc#mydomain.com", "Enquiry");
mail.To.Add("abcdef#yahoo.com");
mail.IsBodyHtml = true;
mail.Subject = "Registration";
mail.Body = "Some Text";
mail.Priority = MailPriority.High;
SmtpClient smtp = new SmtpClient("smtp.gmail.com", 587);
//smtp.UseDefaultCredentials = true;
smtp.Credentials = new System.Net.NetworkCredential("xyz#gmail.com", "<my gmail pwd>");
smtp.EnableSsl = true;
//smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
smtp.Send(mail);
But, there is a problem with using gmail. The email will be sent successfully, but the recipient inbox will have the gmail address in the 'from address' instead of the 'from address' mentioned in the code.
To solve this, please follow the steps mentioned at the following link.
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
ActiveUp.Net.Mail.SmtpMessage smtpmsg = new ActiveUp.Net.Mail.SmtpMessage();
smtpmsg.From.Email = "abcd#test.com";
smtpmsg.To.Add(To);
smtpmsg.Bcc.Add("vijay#indiagreat.com");
smtpmsg.Subject = Subject;
smtpmsg.BodyText.Text = Body;
smtpmsg.Send("mail.test.com", "abcd#sss.com", "user#1234", ActiveUp.Net.Mail.SaslMechanism.Login);
simple code works
MailMessage mail = new MailMessage();
mail.To.Add(to);
mail.From = new MailAddress(from);
mail.Subject = subject;
mail.Body = body;
mail.IsBodyHtml = true;
SmtpClient smtp = new SmtpClient("smtp.gmail.com",587);
smtp.EnableSsl = true;
smtp.UseDefaultCredentials = false;
smtp.Credentials = new System.Net.NetworkCredential(address, password);
smtp.Send(mail);

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