GINPRO / SQLの窓と銀プログラマ

using System;
using System.Windows.Forms;
using TKMP.Net;

namespace TKMP_SendMail_Gmail
{
	public partial class Form1 : Form
	{
		public Form1()
		{
			InitializeComponent();
		}

		private void button1_Click(object sender, EventArgs e)
		{

			MailClass mc = new MailClass()
			{
				SmtpServer = "smtp.gmail.com",
				Port = 587,
				User = "アカウント",
				Pass = password.Text,
				Protocol = AuthenticationProtocols.TLS
			};

			var result = mc.SendMail(
				"宛先",
				"自メールアドレス",
				this.subject.Text,
				this.body.Text,
				null,   // 必要な場合、宛先を日本語で
				null,   // 必要な場合、差出人を日本語で
				(MailClass.MailClassErrorArg _e) =>
				{
					this.error.Text = _e.Message;
				}
			);

			if (result)
			{
				MessageBox.Show("メールを送信しました");
			}

		}

	}
}

using System;
using TKMP.Writer;
using TKMP.Net;

namespace TKMP_SendMail_Gmail
{
	class MailClass
	{
		private MailWriter mailWriter = null;

		public string SmtpServer { get; set; }
		public int Port { get; set; }
		public string User { get; set; }
		public string Pass { get; set; }
		public AuthenticationProtocols Protocol { get; set; }

		private string err_message = "";

		public class MailClassErrorArg
		{
			public string Message { get; set; }
		}

		public delegate void MailClassError(MailClassErrorArg e);

		public bool SendMail(string To, string From, string Subject, string Body, string To_J, string From_J, MailClassError mailClassError)
		{
			bool bResult = true;

			mailWriter = new MailWriter();

			try
			{
				mailWriter.ToAddressList.Add(To);
			}
			catch (Exception ex)
			{
				bResult = false;
			}

			// エラー処理
			if (!bResult)
			{
				if (mailClassError != null)
				{
					MailClassErrorArg e = new MailClassErrorArg() { Message = "宛先が正しくありません" };
					mailClassError(e);
				}
				return bResult;
			}

			// From が未指定や正しくない文字列の場合
			try
			{
				mailWriter.FromAddress = From;
			}
			catch (Exception ex)
			{
				mailWriter.FromAddress = "______@gmail.com";
			}

			TextPart textPart = new TextPart(Body);
			mailWriter.MainPart = textPart;

			if (To_J != null)
			{
				mailWriter.Headers.Add("To", To_J + " <" + To + ">");
			}
			else
			{
				mailWriter.Headers.Add("To", To);
			}

			if (From_J != null)
			{
				mailWriter.Headers.Add("From", From_J + " <" + From + ">");
			}
			else
			{
				mailWriter.Headers.Add("From", From);
			}

			mailWriter.Headers.Add("Subject", Subject);
			mailWriter.Headers.Add("X-Mailer", "TKMP Version 3.1.2");

			var logon = new TKMP.Net.AuthLogin(User, Pass);
			SmtpClient smtpClient = new SmtpClient(SmtpServer, Port, logon);
			smtpClient.AuthenticationProtocol = Protocol;

			try
			{
				if (!smtpClient.Connect())
				{
					err_message = "接続に失敗しました";
					bResult = false;
				}
				else
				{
					smtpClient.SendMail(mailWriter);
					smtpClient.Close();
				}
			}
			catch (Exception ex)
			{
				err_message = ex.Message;
				bResult = false;
			}

			// エラー処理
			if (!bResult)
			{
				if (mailClassError != null)
				{
					MailClassErrorArg e = new MailClassErrorArg() { Message = err_message };
					// このメソッドの引数である、ErrorHandler デリゲートを呼び出す
					mailClassError(e);
				}
			}

			return bResult;
		}

		// エラー処理なし
		public bool SendMail(string To, string From, string Subject, string Body, string To_J, string From_J)
		{
			return SendMail(To, From, Subject, Body, To_J, From_J, null);
		}

		// 日本語なし、エラー処理なし
		public bool SendMail(string To, string From, string Subject, string Body)
		{
			return SendMail(To, From, Subject, Body, null, null, null);
		}

	}

}