邮件服务是一般的系统都会拥有和需要的功能，但是对于.NET项目来说，邮件服务的创建和使用会较为的麻烦。.NET对于邮件功能提供了System.Net.Mail用于创建邮件服务，该基础服务提供邮件的基础操作，并且使用也较为的简单。对于真正将该功能使用于项目的人，就会慢慢发现其中的优缺点，甚至有些时候不能忍受其中的问题。在这里介绍一种微软用于替代System.Net.Mail的邮件服务组件MailKit和MimeKit，官网地址：http://www.mimekit.net/。GitHub地址：https://github.com/jstedfast/MimeKit。下面就具体的介绍一下。
一.MailKit和MimeKit基础概述：
MailKit组件的支持的客户端类型比较多，例如SMTP客户端、POP3客户端、IMAP4客户端。该组件是一个跨平台的Email组件，该组件支持.NET 4.0，.NET 4.5，Xamarin.Android，Xamarin.iOS，Windows Phone 8.1等等平台。
MimeKit提供了一个MIME解析器，组件具备的解析特性灵活、性能高、很好的处理各种各样的破碎的MIME格式化。MimeKit的性能实际上与GMime相当。
该组件在安全性的还是比较高的，处理安全的方式较多，SASL认证、支持S / MIME v3.2、支持OpenPGP、支持DKIM签名等等方式。Mailkit组件可以通过CancellationToken取消对应的操作，CancellationToken传播应取消操作的通知，一个的CancellationToken使线程，线程池工作项目之间，或取消合作任务的对象。过实例化CancellationTokenSource对象来创建取消令牌，该对象管理从其CancellationTokenSource.Token属性检索的取消令牌。然后，将取消令牌传递到应该收到取消通知的任意数量的线程，任务或操作。令牌不能用于启动取消。
MailKit组件支持异步操作，在内部编写的有关I/O异步操作的类。
二.创建基础邮件服务：
介绍过MailKit和MimeKit组建的基础信息，接下来就介绍一下如何使用两个组件的基本功能，在这里我将基本操作做了一个简单的封装，一般的项目可以直接引用封装好的类，大家可以根据实际的情况对该组件进行扩展。
1.邮件发送基础服务API
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///
/// 邮件服务API
///
public static class MailServiceApi
{
///
/// 发送邮件
///
///
邮件基础信息
///
发件人基础信息
public static SendResultEntity SendMail(MailBodyEntity mailBodyEntity,
SendServerConfigurationEntity sendServerConfiguration)
{
if (sendServerConfiguration == null)
{
throw new ArgumentNullException();
}
if (sendServerConfiguration == null)
{
throw new ArgumentNullException();
}
var sendResultEntity = new SendResultEntity();
using (var client = new SmtpClient(new ProtocolLogger(CreateMailLog())))
{
client.ServerCertificateValidationCallback = (s, c, h, e) => true;
Connection(mailBodyEntity, sendServerConfiguration, client, sendResultEntity);
if (sendResultEntity.ResultStatus == false)
{
return sendResultEntity;
}
SmtpClientBaseMessage(client);
Authenticate(mailBodyEntity, sendServerConfiguration, client, sendResultEntity);
if (sendResultEntity.ResultStatus == false)
{
return sendResultEntity;
}
Send(mailBodyEntity, sendServerConfiguration, client, sendResultEntity);
if (sendResultEntity.ResultStatus == false)
{
return sendResultEntity;
}
client.Disconnect(true);
}
return sendResultEntity;
}
///
/// 连接服务器
///
///
邮件内容
///
发送配置
///
客户端对象
///
发送结果
public static void Connection(MailBodyEntity mailBodyEntity, SendServerConfigurationEntity sendServerConfiguration,
SmtpClient client, SendResultEntity sendResultEntity)
{
try
{
client.Connect(sendServerConfiguration.SmtpHost, sendServerConfiguration.SmtpPort);
}
catch (SmtpCommandException ex)
{
sendResultEntity.ResultInformation = $"尝试连接时出错:{0}" + ex.Message;
sendResultEntity.ResultStatus = false;
}
catch (SmtpProtocolException ex)
{
sendResultEntity.ResultInformation = $"尝试连接时的协议错误:{0}" + ex.Message;
sendResultEntity.ResultStatus = false;
}
catch (Exception ex)
{
sendResultEntity.ResultInformation = $"服务器连接错误:{0}" + ex.Message;
sendResultEntity.ResultStatus = false;
}
}
///
/// 账户认证
///
///
邮件内容
///
发送配置
///
客户端对象
///
发送结果
public static void Authenticate(MailBodyEntity mailBodyEntity, SendServerConfigurationEntity sendServerConfiguration,
SmtpClient client, SendResultEntity sendResultEntity)
{
try
{
client.Authenticate(sendServerConfiguration.SenderAccount, sendServerConfiguration.SenderPassword);
}
catch (AuthenticationException ex)
{
sendResultEntity.ResultInformation = $"无效的用户名或密码:{0}" + ex.Message;
sendResultEntity.ResultStatus = false;
}
catch (SmtpCommandException ex)
{
sendResultEntity.ResultInformation = $"尝试验证错误:{0}" + ex.Message;
sendResultEntity.ResultStatus = false;
}
catch (SmtpProtocolException ex)
{
sendResultEntity.ResultInformation = $"尝试验证时的协议错误:{0}" + ex.Message;
sendResultEntity.ResultStatus = false;
}
catch (Exception ex)
{
sendResultEntity.ResultInformation = $"账户认证错误:{0}" + ex.Message;
sendResultEntity.ResultStatus = false;
}
}
///
/// 发送邮件
///
///
邮件内容
///
发送配置
///
客户端对象
///
发送结果
public static void Send(MailBodyEntity mailBodyEntity, SendServerConfigurationEntity sendServerConfiguration,
SmtpClient client, SendResultEntity sendResultEntity)
{
try
{
client.Send(MailMessage.AssemblyMailMessage(mailBodyEntity));
}
catch (SmtpCommandException ex)
{
switch (ex.ErrorCode)
{
case SmtpErrorCode.RecipientNotAccepted:
sendResultEntity.ResultInformation = $"收件人未被接受:{ex.Message}";
break;
case SmtpErrorCode.SenderNotAccepted:
sendResultEntity.ResultInformation = $"发件人未被接受:{ex.Message}";
break;
case SmtpErrorCode.MessageNotAccepted:
sendResultEntity.ResultInformation = $"消息未被接受:{ex.Message}";
break;
}
sendResultEntity.ResultStatus = false;
}
catch (SmtpProtocolException ex)
{
sendResultEntity.ResultInformation = $"发送消息时的协议错误:{ex.Message}";
sendResultEntity.ResultStatus = false;
}
catch (Exception ex)
{
sendResultEntity.ResultInformation = $"邮件接收失败:{ex.Message}";
sendResultEntity.ResultStatus = false;
}
}
///
/// 获取SMTP基础信息
///
///
客户端对象
///
public static MailServerInformation SmtpClientBaseMessage(SmtpClient client)
{
var mailServerInformation = new MailServerInformation
{
Authentication = client.Capabilities.HasFlag(SmtpCapabilities.Authentication),
BinaryMime = client.Capabilities.HasFlag(SmtpCapabilities.BinaryMime),
Dsn = client.Capabilities.HasFlag(SmtpCapabilities.Dsn),
EightBitMime = client.Capabilities.HasFlag(SmtpCapabilities.EightBitMime),
Size = client.MaxSize
};
return mailServerInformation;
}
///
/// 创建邮件日志文件
///
///
public static string CreateMailLog()
{
var logPath = AppDomain.CurrentDomain.BaseDirectory + "/DocumentLog/" +
Guid.NewGuid() + ".txt";
if (File.Exists(logPath)) return logPath;
var fs = File.Create(logPath);
fs.Close();
return logPath;
}
}
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2.组装邮件消息：
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///
/// 邮件信息
///
public static class MailMessage
{
///
/// 组装邮件文本/附件邮件信息
///
///
邮件消息实体
///
public static MimeMessage AssemblyMailMessage(MailBodyEntity mailBodyEntity)
{
if (mailBodyEntity == null)
{
throw new ArgumentNullException(nameof(mailBodyEntity));
}
var message = new MimeMessage();
//设置邮件基本信息
SetMailBaseMessage(message, mailBodyEntity);
var multipart = new Multipart("mixed");
//插入文本消息
if (string.IsNullOrEmpty(mailBodyEntity.MailTextBody) == false)
{
var alternative = new MultipartAlternative
{
AssemblyMailTextMessage(mailBodyEntity.MailTextBody, mailBodyEntity.MailBodyType)
};
multipart.Add(alternative);
}
//插入附件
if (mailBodyEntity.MailFilePath != null && File.Exists(mailBodyEntity.MailFilePath) == false)
{
var mimePart = AssemblyMailAttachmentMessage(mailBodyEntity.MailFileType, mailBodyEntity.MailFileSubType,
mailBodyEntity.MailFilePath);
multipart.Add(mimePart);
}
//组合邮件内容
message.Body = multipart;
return message;
}
///
/// 设置邮件基础信息
///
///
///
///
public static MimeMessage SetMailBaseMessage(MimeMessage minMessag, MailBodyEntity mailBodyEntity)
{
if (minMessag == null)
{
throw new ArgumentNullException();
}
if (mailBodyEntity == null)
{
throw new ArgumentNullException();
}
//插入发件人
minMessag.From.Add(new MailboxAddress(mailBodyEntity.Sender, mailBodyEntity.SenderAddress));
//插入收件人
foreach (var recipients in mailBodyEntity.Recipients)
{
minMessag.To.Add(new MailboxAddress(recipients));
}
//插入抄送人
foreach (var cC in mailBodyEntity.Cc)
{
minMessag.Cc.Add(new MailboxAddress(cC));
}
//插入主题
minMessag.Subject = mailBodyEntity.Subject;
return minMessag;
}
///
/// 组装邮件文本信息
///
///
邮件文本内容
///
邮件文本类型(plain,html,rtf,xml)
///
public static TextPart AssemblyMailTextMessage(string mailBody, string textPartType)
{
if (string.IsNullOrEmpty(mailBody))
{
throw new ArgumentNullException();
}
if (string.IsNullOrEmpty(textPartType))
{
throw new ArgumentNullException();
}
var textBody = new TextPart(textPartType)
{
Text = mailBody
};
return textBody;
}
///
/// 组装邮件附件信息
///
///
附件类型(image,application)
///
附件子类型
///
附件路径
///
public static MimePart AssemblyMailAttachmentMessage(string fileAttachmentType, string fileAttachmentSubType, string fileAttachmentPath)
{
if (string.IsNullOrEmpty(fileAttachmentSubType))
{
throw new ArgumentNullException();
}
if (string.IsNullOrEmpty(fileAttachmentType))
{
throw new ArgumentNullException();
}
if (string.IsNullOrEmpty(fileAttachmentPath))
{
throw new ArgumentNullException();
}
var attachment = new MimePart(fileAttachmentType, fileAttachmentSubType)
{
Content = new MimeContent(File.OpenRead(fileAttachmentPath)),
ContentDisposition = new ContentDisposition(ContentDisposition.Attachment),
ContentTransferEncoding = ContentEncoding.Base64,
FileName = Path.GetFileName(fileAttachmentPath)
};
return attachment;
}
}
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3.邮件基础服务实体：
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///
/// 邮件内容实体
///
public class MailBodyEntity
{
///
/// 邮件文本内容
///
