System.Net.Mail

MailMessage

Here is the example of creating of mail message with attachments. After creating we send this message with the help of SmtpClient class. Default 25 port is used here.

public class clsMail
{
    private static bool SendMail(string mailfrom, List<string>replytos, List<string> mailtos, List<string> mailccs, List<string> mailbccs, string body, string subject, List<string> Attachment)
    {
        try
        {
            using(MailMessage MyMail = new MailMessage())
            {
                MyMail.From = new MailAddress(mailfrom);
                foreach (string mailto in mailtos)
                    MyMail.To.Add(mailto);

                if (replytos != null && replytos.Any())
                {
                    foreach (string replyto in replytos)
                        MyMail.ReplyToList.Add(replyto);
                }

                if (mailccs != null && mailccs.Any())
                {
                    foreach (string mailcc in mailccs)
                        MyMail.CC.Add(mailcc);
                }

                if (mailbccs != null && mailbccs.Any())
                {
                    foreach (string mailbcc in mailbccs)
                        MyMail.Bcc.Add(mailbcc);
                }                         

                MyMail.Subject = subject;
                MyMail.IsBodyHtml = true;
                MyMail.Body = body;
                MyMail.Priority = MailPriority.Normal;

                if (Attachment != null && Attachment.Any())
                {
                    System.Net.Mail.Attachment attachment;
                    foreach (var item in Attachment)
                    {
                        attachment = new System.Net.Mail.Attachment(item);
                        MyMail.Attachments.Add(attachment);
                    }
                }

                SmtpClient smtpMailObj = new SmtpClient();
                smtpMailObj.Host = "your host";
                smtpMailObj.Port = 25;
                smtpMailObj.Credentials = new System.Net.NetworkCredential("uid", "pwd");

                smtpMailObj.Send(MyMail);
                return true;
            }
        }
        catch
        {
            return false;
        }
    }
}

Mail with Attachment

MailMessage represents mail message which can be sent further using SmtpClient class. Several attachments (files) can be added to mail message.

using System.Net.Mail;

using(MailMessage myMail = new MailMessage())
{
     Attachment attachment = new Attachment(path);
     myMail.Attachments.Add(attachment);

     // further processing to send the mail message

}

Remarks

It is important to Dispose a System.Net.MailMessage because every single attachment contains a Stream and these Streams need to be freed as soon as possible. The using statement ensures that the Disposable object is Disposed also in case of Exceptions