发送电子邮件也是项目开发当中经常用到的功能，这里我整理了一个发送电子邮件（带附件，支持多用户发送，主送、抄送）的类库，供大家参考。
先上两个实体类，用于封装成Mail对象。
/// <summary>
/// 发送邮件请求
/// </summary>
public class MailRequest
{
#region PrivateFields
/// <summary>
/// 文件名
/// </summary>
private string _fromField;
/// <summary>
/// 返送到
/// </summary>
private string _toField;
/// <summary>
/// 抄送
/// </summary>
private string _copyField;
/// <summary>
/// 附件
/// </summary>
private string _bccField;
/// <summary>
/// 标题
/// </summary>
private string _subjectField;
/// <summary>
/// 发送人名
/// </summary>
private string _bodyField;
/// <summary>
/// 类容
/// </summary>
private MailRequestAttachments[] _attachmentsField;
#endregion
/// <summary>
/// 发送人，多个人以分号;间隔
/// </summary>
public string From
{
get
{
return this._fromField;
}
set
{
this._fromField = value;
}
}
/// <summary>
/// 收件人，多个人以分号;间隔
/// </summary>
public string To
{
get
{
return this._toField;
}
set
{
this._toField = value;
}
}
/// <summary>
/// 抄送人，多个人以分号;间隔
/// </summary>
public string CC
{
get
{
return this._copyField;
}
set
{
this._copyField = value;
}
}
/// <summary>
/// 秘密抄送人，多个人以分号;间隔
/// </summary>
public string Bcc
{
get
{
return this._bccField;
}
set
{
this._bccField = value;
}
}
/// <summary>
/// 主题
/// </summary>
public string Subject
{
get
{
return this._subjectField;
}
set
{
this._subjectField = value;
}
}
/// <summary>
/// 内容
/// </summary>
public string Body
{
get
{
return this._bodyField;
}
set
{
this._bodyField = value;
}
}
/// <summary>
/// 附件列表
/// </summary>
public MailRequestAttachments[] Attachments
{
get
{
return this._attachmentsField;
}
set
{
this._attachmentsField = value;
}
}
}
/// <summary>
/// 发送邮件请求附件
/// </summary>
public class MailRequestAttachments
{
#region PrivateFields
/// <summary>
/// 文件名
/// </summary>
private string _fileNameField;
/// <summary>
/// 文件内容
/// </summary>
private byte[] _fileDataField;
#endregion
/// <summary>
/// 文件名
/// </summary>
public string FileName
{
get
{
return this._fileNameField;
}
set
{
this._fileNameField = value;
}
}
/// <summary>
/// 文件内容
/// </summary>
public byte[] FileData
{
get
{
return this._fileDataField;
}
set
{
this._fileDataField = value;
}
}
}附件的内容很简单，因为在网络传输当中，是以字节流的形式传输的，因此附件的传输需要转换成字节流数组。
/// <summary>
/// 邮件帮助类
/// </summary>
public static class MailHelper
{
/// <summary>
/// 发送邮件
/// </summary>
/// <param name="request">邮件内容对象</param>
/// <returns>发送邮件所遇到的异常</returns>
public static string SendMail(MailRequest request)
{
try
{
MailMessage mail = new MailMessage();
if (string.IsNullOrEmpty(request.From))
{
request.From = WebConfigurationManager.AppSettings["DefaultMailFrom"];
}
mail.From = new MailAddress(request.From);
PaserMailAddress(request.To, mail.To);
PaserMailAddress(request.CC, mail.CC);
PaserMailAddress(request.Bcc, mail.Bcc);
mail.Subject = request.Subject;
mail.SubjectEncoding = System.Text.Encoding.UTF8;
mail.Body = request.Body;
mail.ReplyTo = new MailAddress(request.From);
mail.IsBodyHtml = true;
if (request.Attachments != null && request.Attachments.Length > 0)
{
for (int i = 0; i < request.Attachments.Length; i++)
{
Attachment mailAttach = new Attachment(ByteArrayToStream(request.Attachments[i].FileData), request.Attachments[i].FileName);
mail.Attachments.Add(mailAttach);
}
}
if (string.IsNullOrEmpty(WebConfigurationManager.AppSettings["SMTPSERVER"]))
{
throw new ApplicationException("邮件服务无效");
}
//Smtp Server
SmtpClient mailClient = new SmtpClient(WebConfigurationManager.AppSettings["SMTPSERVER"]);
if (!string.IsNullOrEmpty(WebConfigurationManager.AppSettings["SMTPSERVERPORT"]))
{
//端口号
try
{
mailClient.Port = Int32.Parse(WebConfigurationManager.AppSettings["SMTPSERVERPORT"]);
}
catch
{
return "SMTP服务器端口设置错误，端口必须设置为数值型";
}
}
if (!string.IsNullOrEmpty(WebConfigurationManager.AppSettings["MAILUSER"]))
{
mailClient.Credentials = new System.Net.NetworkCredential(WebConfigurationManager.AppSettings["MAILUSER"], WebConfigurationManager.AppSettings["MAILUSERPW"]);
mailClient.DeliveryMethod = SmtpDeliveryMethod.Network;
}
else
{
mailClient.Credentials = CredentialCache.DefaultNetworkCredentials;
}
mailClient.Send(mail);
mail.Dispose();
return "邮件发送成功。";
}
catch (SmtpFailedRecipientsException e)
{
return e.Message;
}
catch (SmtpFailedRecipientException e)
{
return e.Message;
}
catch (SmtpException e)
{
return e.Message;
}
catch (Exception e)
{
return e.Message;
}
}
/// <summary>
/// 解析分解邮件地址
/// </summary>
/// <param name="mailAddress">邮件地址</param>
/// <param name="mailCollection">邮件对象</param>
private static void PaserMailAddress(string mailAddress, MailAddressCollection mailCollection)
{
if (string.IsNullOrEmpty(mailAddress))
{
return;
}
char[] separator = new char[2] { ',', ';' };
string[] addressArray = mailAddress.Split(separator);
foreach (string address in addressArray)
{
if (address.Trim() == string.Empty)
{
continue;
}
mailCollection.Add(new MailAddress(address));
}
}
/// <summary>
/// 字节数组转换为流
/// </summary>
/// <param name="byteArray">字节数组</param>
/// <returns>Stream</returns>
private static Stream ByteArrayToStream(byte[] byteArray)
{
MemoryStream mstream = new MemoryStream(byteArray);
return mstream;
}
}这是一个邮件助手类，定义成static，无需实例化，直接类名.方法名的形式调用。
只需要上述3个类就可以实现发送Email了，由于上面引用的是web.config里面的信息（asp.net等命名空间，如果是winform等需要自己修改一下），这里还需要配置一下web.config，如下所示：
<appSettings>
<!--邮件发送配置-->
<add key="SMTPSERVER" value="smtp.qq.com"/>
<!--这是服务器邮箱的地址，如果是新浪，则填 smtp.sina.com-->
<add key="MAILUSER" value="xxx"/>
<!--注意！这是对应服务器邮箱的账号-->
<add key="MAILUSERPW" value="yyy"/>
<!--注意！这是对应服务器邮箱的账号密码-->
</appSettings>最后上一个测试方法，在主函数当中或者Page_Load事件中执行即可：
private void SendEmailExample()
{
MailRequest mail = new MailRequest();
mail.Subject = "hello,this is a e-mail sent by asp.net mailhelper.";//主题
mail.Body = "hello,this is a e-mail sent by asp.net mailhelper.<a href='http://blog.csdn.net/guwei4037'>欢迎访问我的博客。</a>";//内容
mail.Bcc = "512122338@qq.com";//秘密抄送人
mail.From = "345822155@qq.com";//发送人
mail.CC = "guwei4037@sina.com";//抄送人
mail.To = "guwei4037@gmail.com";//收件人
//读取文件到bytes
FileStream stream = new FileStream(Path.Combine(Server.MapPath("~"), "doc\\test.txt"), FileMode.OpenOrCreate, FileAccess.Read, FileShare.Read);
byte[] bytes = new byte[stream.Length];
stream.Read(bytes, 0, bytes.Length);
stream.Close();
//附件
MailRequestAttachments attachments = new MailRequestAttachments();
attachments.FileName = "test.txt";
attachments.FileData = bytes;
mail.Attachments = new MailRequestAttachments[] {
attachments
};
string sendMainResult = "-1";
if (!string.IsNullOrEmpty(mail.CC.Replace(";", "")) && !string.IsNullOrEmpty(mail.To.Replace(";", "")))
{
sendMainResult = MailHelper.SendMail(mail);
}
Response.Write(sendMainResult);
}发送邮件成功，附件也能正常打开，而且多个用户都收到了电子邮件。截图为证。
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最近一个朋友问我说，我上面的这段发送邮件的代码出问题了，出错截图如下：
心想该不是qq邮箱SMTP设置没打开吧，打开邮箱一看是打开的。
注意下面的一段温馨提示：登录第三方客户端时，密码框请输入“授权码”进行验证。难道是qq邮箱的安全机制修改过了？
按照提示，发送了短信，收到了授权码。把原来程序中的发送邮箱账号的明文密码修改成这个授权码，再在程序中加如下两行代码即可。
mailClient.EnableSsl = true; mailClient.UseDefaultCredentials = false;
