GMail SMTP via C# .Net errors on all ports

Question

I\'ve been trying for a whlie on this, and have so far been failing miserably. My most recent attempt was lifted from this stack code here: Sending email through Gmail SMT

Answer 1

I tried your code, and it works prefectly with port 587, but not with 465.

Have you checked the fire wall? Try from the command line "Telnet smtp.gmail.com 587" If you get "220 mx.google.com ESMTP...." back, then the port is open. If not, it is something that blocks you call.

Daniel

Answer 2

There are two ways to do SMTP over SSL: Explicit and Implicit. Explicit means you connect to a normal SMTP port (usually 25 or 587) in plaintext, then issue the “starttls” command to switch to SSL-mode. Implicit means you connect to a port that expects everything to be SSL (usually 465).

Asp.net use “System.Net.Mail.SmtpClient()” to send Email. The main problem is SmtpClient does not support implicit SSL connections, but does support explicit connections (System.Net.Mail with SSL to authenticate against port 465). So, if the mail server(SMTP) do not support Explicit connection, it fails to send email and show messages like “Connection timeout“, “The message could not be sent to the SMTP server. The transport error code was 0x80040217. The server response was not available” etc.

To solve this issue in ASP.net we can use the Collaboration Data Objects (CDO) for Windows 2000 library (Cdosys.dll) to send an e-mail message with attachments. Microsoft Outlook use this DLL to send email. In your ASP.net solution, you have to add referance “Microsoft CDO for windows 2000 Library“. It will add two marked dll in Bin folder.

Now do the bellow code in C#.net:

public static void SendMail(string FromName, string FromEmail, string ReceiverEmail, string CC, string BCC, string subj, string Mssg)
{
 const var cdoSendUsingPort = 2;
 const var cdoBasicAuth = 1;
 const var cdoTimeout = 60;
 var mailServer = "mail.XXXXXXX.net";
 var SMTPport = 465;
 var mailusername = "yyy@XXXXXXX.net";
 var mailpassword = "PPPPXXXX";
 var objEmail = CreateObject("CDO.Message");
 var objConf = objEmail.Configuration;
 var objFlds = objConf.Fields;
 objFlds.Item("http://schemas.microsoft.com/cdo/configuration/sendusing") = cdoSendUsingPort;
 objFlds.Item("http://schemas.microsoft.com/cdo/configuration/smtpserver") = mailServer;
 objFlds.Item("http://schemas.microsoft.com/cdo/configuration/smtpserverport") = SMTPport;
 objFlds.Item("http://schemas.microsoft.com/cdo/configuration/smtpusessl") = true;
 objFlds.Item("http://schemas.microsoft.com/cdo/configuration/smtpconnectiontimeout") = cdoTimeout;
 objFlds.Item("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate") = cdoBasicAuth;
 objFlds.Item("http://schemas.microsoft.com/cdo/configuration/sendusername") = mailusername;
 objFlds.Item("http://schemas.microsoft.com/cdo/configuration/sendpassword") = mailpassword;
 objFlds.Update();
 objEmail.To = ReceiverEmail;
 objEmail.From = FromEmail;
 objEmail.CC = CC;
 objEmail.BCC = BCC;
 objEmail.Subject = subj;
 objEmail.HTMLBody = Mssg;
 objEmail.Send();
}

In VB.net

Public Shared Sub SendMail(ByVal FromName As String, ByVal FromEmail As String, ByVal ReceiverEmail As String, ByVal CC As String, ByVal BCC As String, ByVal subj As String, ByVal Mssg As String)

''#################Sending Email##########################

Const cdoSendUsingPort = 2 ' Send the message using SMTP
 Const cdoBasicAuth = 1 ' Clear-text authentication
 Const cdoTimeout = 60 ' Timeout for SMTP in seconds

Dim mailServer = "mail.XXXXXXX.net"
 Dim SMTPport = 465
 Dim mailusername = "yyy@XXXXXXX.net"
 Dim mailpassword = "PPPPXXXX"




Dim objEmail = CreateObject("CDO.Message")
 Dim objConf = objEmail.Configuration
 Dim objFlds = objConf.Fields

With objFlds
 .Item("http://schemas.microsoft.com/cdo/configuration/sendusing") = cdoSendUsingPort
 .Item("http://schemas.microsoft.com/cdo/configuration/smtpserver") = mailServer
 .Item("http://schemas.microsoft.com/cdo/configuration/smtpserverport") = SMTPport
 .Item("http://schemas.microsoft.com/cdo/configuration/smtpusessl") = True
 .Item("http://schemas.microsoft.com/cdo/configuration/smtpconnectiontimeout") = cdoTimeout
 .Item("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate") = cdoBasicAuth
 .Item("http://schemas.microsoft.com/cdo/configuration/sendusername") = mailusername
 .Item("http://schemas.microsoft.com/cdo/configuration/sendpassword") = mailpassword
 .Update()
 End With

objEmail.To = ReceiverEmail
 objEmail.From = FromEmail
 objEmail.CC = CC
 objEmail.BCC = BCC
 objEmail.Subject = subj
 objEmail.HTMLBody = Mssg
 'objEmail.AddAttachment "C:\report.pdf"
 objEmail.Send()
 End Sub

Referance: Original post Implicit & Explicit SMTP http://help.fogcreek.com/9002/using-an-smtp-server-with-ssl use the Cdosys.dll library to send an e-mail message with attachments https://support.microsoft.com/en-us/help/310212/how-to-use-the-cdosys-dll-library-to-send-an-e-mail-message-with-attac

Answer 3

Your private network's firewall blocked the ports 587 and 465. You can use default port 25 or enable there ports on firewall

Answer 4

I implemented an email client sometime back that could talk to gmail on both 587 and 465...

Port 25 is the normal unencrypted pop port; not available on gmail.

The other two ports have encryption; 587 uses TLS, 465 uses SSL.

To use 587 you should set SmtpClient.EnableSsl = true.

465 wont work with SmtpClient, it will work with the deprecated class SmtpMail instead.

Answer 5

I ran in to this problem a while ago as well. The problem is that SmtpClient does not support implicit SSL connections, but does support explicit connections (System.Net.Mail with SSL to authenticate against port 465). The previous class of MailMessage (I believe .Net 1.0) did support this but has long been obsolete.

My answer was to call the CDO (Collaborative Data Objects) (http://support.microsoft.com/kb/310212) directly through COM using something like the following:

    /// <summary>
    /// Send an electronic message using the Collaboration Data Objects (CDO).
    /// </summary>
    /// <remarks>http://support.microsoft.com/kb/310212</remarks>
    private void SendTestCDOMessage()
    {
        try
        {
            string yourEmail = "YourUserName@gmail.com";

            CDO.Message message = new CDO.Message();
            CDO.IConfiguration configuration = message.Configuration;
            ADODB.Fields fields = configuration.Fields;

            Console.WriteLine(String.Format("Configuring CDO settings..."));

            // Set configuration.
            // 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. (Hint: This requires the use of "sendusername" and "sendpassword" fields)
            //                                  - cdoNTLM, value 2. The current process security context is used to authenticate with the service.

            ADODB.Field field = fields["http://schemas.microsoft.com/cdo/configuration/smtpserver"];
            field.Value = "smtp.gmail.com";

            field = fields["http://schemas.microsoft.com/cdo/configuration/smtpserverport"];
            field.Value = 465;

            field = fields["http://schemas.microsoft.com/cdo/configuration/sendusing"];
            field.Value = CDO.CdoSendUsing.cdoSendUsingPort;

            field = fields["http://schemas.microsoft.com/cdo/configuration/smtpauthenticate"];
            field.Value = CDO.CdoProtocolsAuthentication.cdoBasic;

            field = fields["http://schemas.microsoft.com/cdo/configuration/sendusername"];
            field.Value = yourEmail;

            field = fields["http://schemas.microsoft.com/cdo/configuration/sendpassword"];
            field.Value = "YourPassword";

            field = fields["http://schemas.microsoft.com/cdo/configuration/smtpusessl"];
            field.Value = "true";

            fields.Update();

            Console.WriteLine(String.Format("Building CDO Message..."));

            message.From = yourEmail;
            message.To = yourEmail;
            message.Subject = "Test message.";
            message.TextBody = "This is a test message. Please disregard.";

            Console.WriteLine(String.Format("Attempting to connect to remote server..."));

            // Send message.
            message.Send();

            Console.WriteLine("Message sent.");
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
    }

Do not forget to browse through your COM references and add the "Microsoft CDO for Windows 200 Library" which should add two references: ADODB, and CDO.

Answer 6

Try this link http://www.google.com/accounts/DisplayUnlockCaptcha on server.

Business Gmail accounts, (or normal gmail accounts don't sure about this one) demands a DisplayUnlockCaptcha for the very first time.