MailKit和MimeKit 收发邮件

新建项目，引用MailKit和MimeKit NuGet包

using CommonTool.MailKit;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ProjectDemo.ConsoleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                var ccList = new List<string>();
                ccList.Add("*****@qq.com");
                var recipients = new List<string>();
                recipients.Add("*****@qq.com");
                var mailBodyEntity = new MailBodyEntity()
                {
                    Body = "这是一个测试邮件body内容<a href='http://www.baidu.com'>123</a>",
                    Cc = ccList,
                    //MailBodyType = "html",
                    MailFiles = new List<MailFile>() {
                        new MailFile { MailFilePath = @"D:\文档\File\20180807165402.png", MailFileSubType = "png", MailFileType = "image" },
                        new MailFile { MailFilePath = @"D:\文档\File\TIM截图20180807165402.png", MailFileSubType = "png", MailFileType = "image" }
                    },
                    Recipients = recipients,
                    Sender = "邮件的发件人",
                    SenderAddress = "111111@qq.com",
                    Subject = "测试邮件是否可以发送的标题",
                };
                var sendServerConfiguration = new SendServerConfigurationEntity()
                {
                    SenderPassword = "123456",
                    SmtpPort = 465,
                    IsSsl = true,
                    MailEncoding = "utf-8",
                    SenderAccount = "11111@qq.com",
                    SmtpHost = "smtp.qq.com",

                };

                var result=SeedMailHelper.SendMail(mailBodyEntity, sendServerConfiguration);
                ReceiveEmailHelper.ReceiveEmail();
                ReceiveEmailHelper.DownloadBodyParts();
                Console.WriteLine("成功！");
                Console.ReadLine();
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
        }
    }
}

发送邮件

using MailKit;
using MailKit.Net.Smtp;
using MailKit.Security;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CommonTool.MailKit
{
    /// <summary>
    /// 发送邮件
    /// </summary>
    public static class SeedMailHelper
    {
        /// <summary>
        /// 发送邮件
        /// </summary>
        /// <param name="mailBodyEntity">邮件基础信息</param>
        /// <param name="sendServerConfiguration">发件人基础信息</param>
        public static SendResultEntity SendMail(MailBodyEntity mailBodyEntity,
            SendServerConfigurationEntity sendServerConfiguration)
        {
            if (mailBodyEntity == null)
            {
                throw new ArgumentNullException();
            }

            if (sendServerConfiguration == null)
            {
                throw new ArgumentNullException();
            }

            var sendResultEntity = new SendResultEntity();

            using (var client = new SmtpClient(new ProtocolLogger(MailMessage.CreateMailLog())))
            {
                client.ServerCertificateValidationCallback = (s, c, h, e) => true;

                Connection(mailBodyEntity, sendServerConfiguration, client, sendResultEntity);

                if (sendResultEntity.ResultStatus == false)
                {
                    return sendResultEntity;
                }

                SmtpClientBaseMessage(client);

                // Note: since we don't have an OAuth2 token, disable
                // the XOAUTH2 authentication mechanism.
                client.AuthenticationMechanisms.Remove("XOAUTH2");

                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;
        }

        /// <summary>
        /// 连接服务器
        /// </summary>
        /// <param name="mailBodyEntity">邮件内容</param>
        /// <param name="sendServerConfiguration">发送配置</param>
        /// <param name="client">客户端对象</param>
        /// <param name="sendResultEntity">发送结果</param>
        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;
            }
        }

        /// <summary>
        /// 账户认证
        /// </summary>
        /// <param name="mailBodyEntity">邮件内容</param>
        /// <param name="sendServerConfiguration">发送配置</param>
        /// <param name="client">客户端对象</param>
        /// <param name="sendResultEntity">发送结果</param>
        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;
            }
        }

        /// <summary>
        /// 发送邮件
        /// </summary>
        /// <param name="mailBodyEntity">邮件内容</param>
        /// <param name="sendServerConfiguration">发送配置</param>
        /// <param name="client">客户端对象</param>
        /// <param name="sendResultEntity">发送结果</param>
        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;
            }
        }

        /// <summary>
        /// 获取SMTP基础信息
        /// </summary>
        /// <param name="client">客户端对象</param>
        /// <returns></returns>
        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;
        }
    }
}

基础类

using MimeKit;
using MimeKit.Text;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CommonTool.MailKit
{
    /// <summary>
    /// 邮件信息
    /// </summary>
    public static class MailMessage
    {
        /// <summary>
        /// 组装邮件文本/附件邮件信息
        /// </summary>
        /// <param name="mailBodyEntity">邮件消息实体</param>
        /// <returns></returns>
        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.Body))
            {
                var alternative = new MultipartAlternative
                {
                    AssemblyMailTextMessage(mailBodyEntity.Body, mailBodyEntity.MailBodyType)
                 };
                multipart.Add(alternative);
            }

            //插入附件
            foreach (var mailFile in mailBodyEntity.MailFiles)
            {
                if (mailFile.MailFilePath != null && File.Exists(mailFile.MailFilePath))
                {
                    var mimePart = AssemblyMailAttachmentMessage(mailFile.MailFileType, mailFile.MailFileSubType,
                         mailFile.MailFilePath);
                    multipart.Add(mimePart);
                }
            }

            //组合邮件内容
            message.Body = multipart;
            return message;
        }

        /// <summary>
        /// 设置邮件基础信息
        /// </summary>
        /// <param name="minMessag"></param>
        /// <param name="mailBodyEntity"></param>
        /// <returns></returns>
        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
            if(mailBodyEntity.Recipients.Any())
            {
                foreach (var recipients in mailBodyEntity.Recipients)
                {
                    minMessag.To.Add(new MailboxAddress(recipients));
                }
            }

            //插入抄送人
            if (mailBodyEntity.Cc!=null&&mailBodyEntity.Cc.Any())
            {
                foreach (var cC in mailBodyEntity.Cc)
                {
                    minMessag.Cc.Add(new MailboxAddress(cC));
                }
            }

            //插入密送人
            if (mailBodyEntity.Bcc != null && mailBodyEntity.Bcc.Any())
            {
                foreach (var bcc in mailBodyEntity.Bcc)
                {
                    minMessag.Bcc.Add(new MailboxAddress(bcc));
                }
            }

            //插入主题
            minMessag.Subject = mailBodyEntity.Subject;
            return minMessag;
        }

        /// <summary>
        /// 组装邮件文本信息
        /// </summary>
        /// <param name="mailBody">邮件内容</param>
        /// <param name="textPartType">邮件类型(plain,html,rtf,xml)</param>
        /// <returns></returns>
        public static TextPart AssemblyMailTextMessage(string mailBody, TextFormat textPartType)
        {
            if (string.IsNullOrEmpty(mailBody))
            {
                throw new ArgumentNullException();
            }
            //var textBody = new TextPart(textPartType)
            //{
            //    Text = mailBody,
            //};

            //处理查看源文件有乱码问题
            var textBody = new TextPart(textPartType);
            textBody.SetText(Encoding.Default, mailBody);
            return textBody;
        }

        /// <summary>
        /// 组装邮件附件信息
        /// </summary>
        /// <param name="fileAttachmentType">附件类型(image,application)</param>
        /// <param name="fileAttachmentSubType">附件子类型 </param>
        /// <param name="fileAttachmentPath">附件路径</param>
        /// <returns></returns>
        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 fileName = Path.GetFileName(fileAttachmentPath);
            var attachment = new MimePart(fileAttachmentType, fileAttachmentSubType)
            {
                Content = new MimeContent(File.OpenRead(fileAttachmentPath)),
                ContentDisposition = new ContentDisposition(ContentDisposition.Attachment),
                ContentTransferEncoding = ContentEncoding.Base64,
                //FileName = fileName,
            };

            //qq邮箱附件文件名中文乱码问题
            //var charset = "GB18030";
            attachment.ContentType.Parameters.Add(Encoding.Default, "name", fileName);
            attachment.ContentDisposition.Parameters.Add(Encoding.Default, "filename", fileName);

            //处理文件名过长
            foreach (var param in attachment.ContentDisposition.Parameters)
                param.EncodingMethod = ParameterEncodingMethod.Rfc2047;
            foreach (var param in attachment.ContentType.Parameters)
                param.EncodingMethod = ParameterEncodingMethod.Rfc2047;

            return attachment;
        }

        /// <summary>
        /// 创建邮件日志文件
        /// </summary>
        /// <returns></returns>
        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;

        }
    }
}

实体

using MimeKit.Text;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CommonTool.MailKit
{
    /// <summary>
    /// 邮件内容实体
    /// </summary>
    public class MailBodyEntity
    {
        ///// <summary>
        ///// 邮件文本内容
        ///// </summary>
        //public string MailTextBody { get; set; }

        /// <summary>
        /// 邮件内容类型
        /// </summary>
        public TextFormat MailBodyType { get; set; } = TextFormat.Html;

        /// <summary>
        /// 邮件附件集合
        /// </summary>
        public List<MailFile> MailFiles { get; set; }

        /// <summary>
        /// 收件人
        /// </summary>
        public List<string> Recipients { get; set; }

        /// <summary>
        /// 抄送
        /// </summary>
        public List<string> Cc { get; set; }

        /// <summary>
        /// 密送
        /// </summary>
        public List<string> Bcc { get; set; }

        /// <summary>
        /// 发件人
        /// </summary>
        public string Sender { get; set; }

        /// <summary>
        /// 发件人地址
        /// </summary>
        public string SenderAddress { get; set; }

        /// <summary>
        /// 邮件主题
        /// </summary>
        public string Subject { get; set; }

        /// <summary>
        /// 邮件内容
        /// </summary>
        public string Body { get; set; }
    }

    public class MailFile
    {
        /// <summary>
        /// 邮件附件文件类型 例如：图片 MailFileType="image"
        /// </summary>
        public string MailFileType { get; set; }

        /// <summary>
        /// 邮件附件文件子类型 例如：图片 MailFileSubType="png"
        /// </summary>
        public string MailFileSubType { get; set; }

        /// <summary>
        /// 邮件附件文件路径  例如：图片 MailFilePath=@"C:\Files\123.png"
        /// </summary>
        public string MailFilePath { get; set; }
    }

    /// <summary>
    /// 邮件服务器基础信息
    /// </summary>
    public class MailServerInformation
    {
        /// <summary>
        /// SMTP服务器支持SASL机制类型
        /// </summary>
        public bool Authentication { get; set; }

        /// <summary>
        /// SMTP服务器对消息的大小
        /// </summary>
        public uint Size { get; set; }

        /// <summary>
        /// SMTP服务器支持传递状态通知
        /// </summary>
        public bool Dsn { get; set; }

        /// <summary>
        /// SMTP服务器支持Content-Transfer-Encoding
        /// </summary>
        public bool EightBitMime { get; set; }

        /// <summary>
        /// SMTP服务器支持Content-Transfer-Encoding
        /// </summary>
        public bool BinaryMime { get; set; }

        /// <summary>
        /// SMTP服务器在消息头中支持UTF-8
        /// </summary>
        public string UTF8 { get; set; }
    }

    /// <summary>
    /// 邮件发送结果
    /// </summary>
    public class SendResultEntity
    {
        /// <summary>
        /// 结果信息
        /// </summary>
        public string ResultInformation { get; set; } = "发送成功！";

        /// <summary>
        /// 结果状态
        /// </summary>
        public bool ResultStatus { get; set; } = true;
    }

    /// <summary>
    /// 邮件发送服务器配置
    /// </summary>
    public class SendServerConfigurationEntity
    {
        /// <summary>
        /// 邮箱SMTP服务器地址
        /// </summary>
        public string SmtpHost { get; set; }

        /// <summary>
        /// 邮箱SMTP服务器端口
        /// </summary>
        public int SmtpPort { get; set; }

        /// <summary>
        /// 是否启用IsSsl
        /// </summary>
        public bool IsSsl { get; set; }

        /// <summary>
        /// 邮件编码
        /// </summary>
        public string MailEncoding { get; set; }

        /// <summary>
        /// 邮箱账号
        /// </summary>
        public string SenderAccount { get; set; }

        /// <summary>
        /// 邮箱密码
        /// </summary>
        public string SenderPassword { get; set; }

    }
}

接收

using MailKit;
using MailKit.Net.Imap;
using MailKit.Search;
using MailKit.Security;
using MimeKit;
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CommonTool.MailKit
{
    /// <summary>
    /// 跟投邮件服务API
    /// </summary>
    public static class ReceiveEmailHelper
    {
        /// <summary>
        /// 设置发件人信息
        /// </summary>
        /// <returns></returns>
        public static SendServerConfigurationEntity SetSendMessage()
        {
            var sendServerConfiguration = new SendServerConfigurationEntity
            {
                SmtpHost = ConfigurationManager.AppSettings["SmtpServer"],
                SmtpPort = int.Parse(ConfigurationManager.AppSettings["SmtpPort"]),
                IsSsl = Convert.ToBoolean(ConfigurationManager.AppSettings["IsSsl"]),
                MailEncoding = ConfigurationManager.AppSettings["MailEncoding"],
                SenderAccount = ConfigurationManager.AppSettings["SenderAccount"],
                SenderPassword = ConfigurationManager.AppSettings["SenderPassword"]
            };
            return sendServerConfiguration;
        }

        /// <summary>
        /// 接收邮件
        /// </summary>
        public static void ReceiveEmail()
        {
            var sendServerConfiguration = SetSendMessage();

            if (sendServerConfiguration == null)
            {
                throw new ArgumentNullException();
            }

            using (var client = new ImapClient(new ProtocolLogger(MailMessage.CreateMailLog())))
            {
                client.Connect(sendServerConfiguration.SmtpHost, sendServerConfiguration.SmtpPort,
                    SecureSocketOptions.SslOnConnect);
                client.Authenticate(sendServerConfiguration.SenderAccount, sendServerConfiguration.SenderPassword);
                client.Inbox.Open(FolderAccess.ReadOnly);
                var uids = client.Inbox.Search(SearchQuery.All);
                foreach (var uid in uids)
                {
                    var message = client.Inbox.GetMessage(uid);
                    message.WriteTo($"{uid}.eml");
                }

                client.Disconnect(true);
            }
        }

        /// <summary>
        /// 下载邮件内容
        /// </summary>
        public static void DownloadBodyParts()
        {
            var sendServerConfiguration = SetSendMessage();

            using (var client = new ImapClient())
            {
                client.Connect(sendServerConfiguration.SmtpHost, sendServerConfiguration.SmtpPort,
                    SecureSocketOptions.SslOnConnect);
                client.Authenticate(sendServerConfiguration.SenderAccount, sendServerConfiguration.SenderPassword);
                client.Inbox.Open(FolderAccess.ReadOnly);

                // 搜索Subject标题包含“MimeKit”或“MailKit”的邮件
                var query = SearchQuery.SubjectContains("MimeKit").Or(SearchQuery.SubjectContains("MailKit"));
                var uids = client.Inbox.Search(query);

                // 获取搜索结果的摘要信息（我们需要UID和BODYSTRUCTURE每条消息，以便我们可以提取文本正文和附件）
                var items = client.Inbox.Fetch(uids, MessageSummaryItems.UniqueId | MessageSummaryItems.BodyStructure);

                foreach (var item in items)
                {
                    // 确定一个目录来保存内容
                    var directory = Path.Combine(AppDomain.CurrentDomain.BaseDirectory + "/MailBody", item.UniqueId.ToString());

                    Directory.CreateDirectory(directory);

                    // IMessageSummary.TextBody是一个便利的属性，可以为我们找到“文本/纯文本”的正文部分
                    var bodyPart = item.TextBody;

                    // 下载'text / plain'正文部分
                    var body = (TextPart)client.Inbox.GetBodyPart(item.UniqueId, bodyPart);

                    // TextPart.Text是一个便利的属性，它解码内容并将结果转换为我们的字符串
                    var text = body.Text;

                    File.WriteAllText(Path.Combine(directory, "body.txt"), text);

                    // 现在遍历所有附件并将其保存到磁盘
                    foreach (var attachment in item.Attachments)
                    {
                        // 像我们对内容所做的那样下载附件
                        var entity = client.Inbox.GetBodyPart(item.UniqueId, attachment);

                        // 附件可以是message / rfc822部件或常规MIME部件
                        var messagePart = entity as MessagePart;
                        if (messagePart != null)
                        {
                            var rfc822 = messagePart;

                            var path = Path.Combine(directory, attachment.PartSpecifier + ".eml");

                            rfc822.Message.WriteTo(path);
                        }
                        else
                        {
                            var part = (MimePart)entity;

                            // 注意：这可能是空的，但大多数会指定一个文件名
                            var fileName = part.FileName;

                            var path = Path.Combine(directory, fileName);

                            // decode and save the content to a file
                            using (var stream = File.Create(path))
                                part.Content.DecodeTo(stream);
                        }
                    }
                }

                client.Disconnect(true);
            }
        }
    }
}

https://blog.csdn.net/sd7o95o/article/details/79493045