C# 4.0 Send email

Fast way:

//Use class: MailMessage and SmtpClient

using System.Net.Mail;
using System.Net;

[...]

private static readonly object _lockTaken = new Object();
private readonly MailAddressCollection _sendToList; // collecton emails

[...]
            lock (_lockTaken) //multithread security
            {

                try
                {
    
                    using (MailMessage mailMessage = new MailMessage())
                    {
                        mailMessage.From = _sendFrom; //MailAddress
                        mailMessage.Subject = _emailSubject; //string
                        mailMessage.Body = emailBodyMessage; //string
                        mailMessage.Priority = mailPriority; //MailPriority

                        foreach (MailAddress address in _sendToList)
                        {
                            mailMessage.To.Add(address);
                        }

                        using (SmtpClient client = new SmtpClient(_sendFromSmtp))
                        {
                            //SMTP settings can be different, my is below

                            client.Credentials = CredentialCache.DefaultNetworkCredentials;

                            client.Send(mailMessage);
                        }
                    }

                }
                catch (Exception ex)
                {
                    ...
                }

             }//lock

DONE.





Mail Expt package (includes IMAP, POP3, SMTP, Template Engine, Mail Merge, Bounce Inspector, and Email Validator). It helps you to compose, send, read emails as well as filter bounced email messages. In addition, you can validate email addresses with a single line of code. You can find more info about them at the following webblogs: IMAP Blog, POP3 Blog, and SMTP Blog.


Setting config file:
<mailSettings> Element

Namespaces:
Expand System.Net.Mail Namespace
System.Net.Sockets Namespace
System.Net.Security Namespace
System.Net.Mime Namespace
  
Basic classes:
SmtpClient Class
MailMessage Class
MailAddress Class
Attachment Class

SmtpStatusCode Enumeration

Specify exceptions:
SmtpFailedRecipientsException Class (more than one recipients)
SmtpFailedRecipientException Class (one recipient)
SmtpException Class


Articles:
http://murraymac.net/70536/Mail.aspx
http://www.asp.net-crawler.com/articles/emails/Catching-sending-emails-using-aspnet-errors-exceptions-handling.aspx
http://www.codeproject.com/Articles/5189/End-to-end-Email-Address-Verification-for-Applicat
http://www.emailarchitect.net/easendmail/sdk/html/smtpmail_deliverynotification.htm
http://luktom.net/e280-wysylanie-maili-w-c
http://csharp.net-informations.com/communications/csharp-smtp-mail.htm
http://www.answersthatwork.com/Download_Area/ATW_Library/Networking/Network__3-SMTP_Server_Status_Codes_and_SMTP_Error_Codes.pdf
http://stackoverflow.com/questions/6213741/net-smtp-send-with-smtpstatuscode-when-should-a-retry-occur
http://stackoverflow.com/questions/384119/net-smtpclient-where-is-pending-outgoing-mail-stored
http://www.codeproject.com/Articles/32434/Adding-Save-functionality-to-Microsoft-Net-Mail-Ma
http://eastgroup.pl/default.aspx?page=13
http://www.blackwasp.co.uk/SendSmtpAsync.aspx
http://www.eggheadcafe.com/articles/20030720.asp
http://www.limilabs.com/blog/read-system-net-mailsettings-smtp-settings-web-confighttp://stackoverflow.com/questions/4599779/reading-system-net-mailsettings-smtp-from-web-config-in-medium-trust-environment
http://www.codeproject.com/Articles/32434/Adding-Save-functionality-to-Microsoft-Net-Mail-Ma
http://support.mailhostbox.com/email-administrators-guide/error-codes
http://www.codicode.com/art/free_asp_net_email_validator_verifier.aspx
http://www.c-sharpcorner.com/UploadFile/kirtan007/check-if-email-address-really-exist-or-not-using-C-Sharp/