ASP.NET Core使用MailKit发送邮件

冷冷的菜哥2025-09-10 12:21

1.添加MailKit依赖

bash 复制代码 
dotnet add package MailKit

2.发送邮件服务

cs 复制代码 
using System.Text;
using dotnet_start.Model;
using MailKit.Net.Smtp;
using MimeKit;
using MimeKit.Text;
using MimeKit.Utils;
using Path = System.IO.Path;

namespace dotnet_start.Services;

public class EmailSendService
{
    public readonly IWebHostEnvironment Env;

    public readonly ILogger<EmailSendService> Logger;

    public EmailSendService(IWebHostEnvironment env, ILogger<EmailSendService> logger)
    {
        Env = env;
        Logger = logger;
    }

    public async Task SendEmailByTextPartAsync(string fromEmail, string toEmail, string subject, string message)
    {
        var mineMessage = new MimeMessage();
        var fromAddress = new MailboxAddress("这是来ASP.NET Core------文本方式邮件", fromEmail);
        mineMessage.From.Add(fromAddress);

        var toAddress = new MailboxAddress("菜哥", toEmail);
        mineMessage.To.Add(toAddress);

        mineMessage.Subject = subject;
        mineMessage.Body = new TextPart(TextFormat.Html)
        {
            Text = message
        };

        await SendBySmtp(fromEmail, mineMessage);
    }

    public async Task SendEmailByHtmlAsync(string fromEmail, string toEmail, string subject, string message)
    {
        var mineMessage = new MimeMessage();
        mineMessage.Subject = subject;
        var fromAddress = new MailboxAddress("这是来ASP.NET Core------HTML方式的邮件", fromEmail);
        mineMessage.From.Add(fromAddress);
        var toAddress = new MailboxAddress("菜哥", toEmail);
        mineMessage.To.Add(toAddress);

        var bodyBuilder = new BodyBuilder();

        var imagePath = Path.Combine(Env.ContentRootPath, "Templates", "img", "vue-js.png");
        if (File.Exists(imagePath))
        {
            // 添加附件
            var mimeEntity = await bodyBuilder.LinkedResources.AddAsync(imagePath);
            mimeEntity.ContentId = MimeUtils.GenerateMessageId();
            bodyBuilder.HtmlBody = $"<p>{message}</p>" +
                                   $"<p><img src=\"cid:{mimeEntity.ContentId}\" alt=\"\" width=\"500\" height=\"300\"/></p>";
        }

        mineMessage.Body = bodyBuilder.ToMessageBody();
        await SendBySmtp(fromEmail, mineMessage);
    }

    public async Task SendEmailByTemplateAsync(string fromEmail, string toEmail, string subject,
        string tempName,
        Dictionary<string, string> variables,
        List<string>? attachments = null,
        List<string>? inlineImages = null)
    {
        var mineMessage = new MimeMessage();
        mineMessage.Subject = subject;

        var fromAddress = new MailboxAddress("ASP.NET Core 模板邮件", fromEmail);
        mineMessage.From.Add(fromAddress);

        var toAddress = new MailboxAddress("菜哥", toEmail);
        mineMessage.To.Add(toAddress);

        var bodyBuilder = new BodyBuilder();

        // 读取模板
        var templatePath = Path.Combine(Env.ContentRootPath, "Templates", tempName);
        if (!File.Exists(templatePath))
        {
            throw new FileNotFoundException($"邮件模板不存在: {templatePath}");
        }


        var templateContent = await File.ReadAllTextAsync(templatePath);

        // 替换变量 {{Key}}
        templateContent = variables.Aggregate(templateContent, (current, kv) => current.Replace($"{{{{{kv.Key}}}}}", kv.Value));

        // 内联图片
        if (inlineImages != null)
        {
            foreach (var imgPath in inlineImages.Where(File.Exists))
            {
                var img = await bodyBuilder.LinkedResources.AddAsync(imgPath);
                var contentId = Path.GetFileNameWithoutExtension(imgPath);
                img.ContentId = contentId;
            }
        }

        // 附件
        if (attachments != null)
        {
            foreach (var filePath in attachments.Where(File.Exists))
            {
                await bodyBuilder.Attachments.AddAsync(filePath);
            }
        }

        bodyBuilder.HtmlBody = templateContent;
        mineMessage.Body = bodyBuilder.ToMessageBody();

        await SendBySmtp(fromEmail, mineMessage);
    }


    public async Task SendEmailByTemplateFormAsync(string fromEmail, string toEmail, string subject, string tempName,
        Dictionary<string, string> variables,
        List<IFormFile>? attachments = null,
        List<IFormFile>? inlineImages = null)
    {
        var mimeMessage = new MimeMessage();
        mimeMessage.Subject = subject;
        mimeMessage.From.Add(new MailboxAddress("ASP.NET Core 模板邮件", fromEmail));
        mimeMessage.To.Add(new MailboxAddress("收件人", toEmail));

        var bodyBuilder = new BodyBuilder();
        try
        {
            // 读取模板
            var templatePath = Path.Combine(Env.ContentRootPath, "Templates", tempName);
            if (!File.Exists(templatePath))
                throw new FileNotFoundException($"邮件模板不存在: {templatePath}");

            var templateContent = await File.ReadAllTextAsync(templatePath);

            // 替换普通变量
            templateContent = variables.Aggregate(templateContent, (current, kv) =>
                current.Replace($"{{{{{kv.Key}}}}}", kv.Value));

            using var tempDir = new TempDirectory(Logger);

            // 内联图片
            if (inlineImages is { Count: > 0 })
            {
                var sb = new StringBuilder();
                foreach (var file in inlineImages.Where(file => file.Length > 0))
                {
                    var fileName = file.FileName;

                    // 读取文件内容到字节数组
                    byte[] bytes;
                    await using (var stream = file.OpenReadStream())
                    {
                        bytes = new byte[stream.Length];
                        var readAsync = await stream.ReadAsync(bytes);
                        if (readAsync == file.Length)
                        {
                            Logger.LogInformation("内联文件==={fileName}，大小==={readAsync} 读取完成", fileName, readAsync);
                        }
                    }

                    await HandlerAttachment(file, bodyBuilder, tempDir, bytes);

                    // 转 Base64
                    var base64 = Convert.ToBase64String(bytes);
                    var ext = Path.GetExtension(fileName).TrimStart('.').ToLower();

                    // 生成对应 img 标签
                    sb.AppendLine($"<img src=\"data:image/{ext};base64,{base64}\" alt=\"{fileName}\" />");
                }

                // 替换模板占位符
                templateContent = templateContent.Replace("{{InlineImages}}", sb.ToString());
            }

            // 处理附件
            if (attachments is { Count: > 0 })
            {
                foreach (var file in attachments.Where(file => file.Length > 0))
                {
                    await HandlerAttachment(file, bodyBuilder, tempDir);
                }
            }

            bodyBuilder.HtmlBody = templateContent;
            mimeMessage.Body = bodyBuilder.ToMessageBody();

            await SendBySmtp(fromEmail, mimeMessage);
        }
        catch (Exception e)
        {
            Console.WriteLine(e);
            throw;
        }
    }

    /// <summary>
    /// 处理附件
    /// </summary>
    /// <param name="file">附件文件</param>
    /// <param name="bodyBuilder">邮件内容构造器</param>
    /// <param name="tempDir">临时目录</param>
    /// <param name="bytes">文件字节</param>
    private async Task HandlerAttachment(IFormFile file, BodyBuilder bodyBuilder, TempDirectory tempDir, byte[]? bytes = null)
    {
        var fileName = file.FileName;
        var fileLength = file.Length;
        var filContentType = file.ContentType;
        var contentType = !string.IsNullOrWhiteSpace(filContentType)
            ? ContentType.Parse(filContentType)
            : new ContentType("application", "octet-stream");
        // 附件小于5M的直接使用内存流，
        if (file.Length < 5 << 20)
        {
            Logger.LogInformation("附件名称: {Name}，大小==={Length}小于5MB使用内存流", fileName, fileLength);
            if (bytes is { Length: > 0 })
            {
                await bodyBuilder.Attachments.AddAsync(fileName, new MemoryStream(bytes), contentType);
            }
            else
            {
                var stream = new MemoryStream();
                await file.CopyToAsync(stream);
                // 重置流位置
                stream.Position = 0;
                await bodyBuilder.Attachments.AddAsync(fileName, stream, contentType);
            }
        }
        else
        {
            using var tempFilePath = new TempFile(tempDir.Path, Logger);
            Logger.LogInformation("附件名称: {Name}，大小==={Length}大于5MB使用临时文件==={@tempFilePath}", fileName, fileLength, tempFilePath.Path);
            await using var stream = new FileStream(tempFilePath.Path, FileMode.Create);
            await file.CopyToAsync(stream);

            var attachment = await bodyBuilder.Attachments.AddAsync(tempFilePath.Path, contentType);
            // 设置附件的文件名为原始文件名
            attachment.ContentDisposition.FileName = fileName;
        }
    }

    private static async Task SendBySmtp(string fromEmail, MimeMessage mineMessage)
    {
        using var smtp = new SmtpClient();
        await smtp.ConnectAsync("smtp.qq.com", 465, true);
        // TODO 设置认证信息------授权码(不是密码)，我这里是以QQ邮箱为例的，QQ邮箱的SMTP服务怎么开桶及授权码，请参照QQ邮箱安全设置相关
        await smtp.AuthenticateAsync(fromEmail, "授权码，请自行参照网上教程");
        await smtp.SendAsync(mineMessage);
        await smtp.DisconnectAsync(true);
    }
}

3.邮件发送控制器

cs 复制代码 
using dotnet_start.Model.Response;
using dotnet_start.Services;
using Microsoft.AspNetCore.Mvc;
using Swashbuckle.AspNetCore.Annotations;
using Path = System.IO.Path;

namespace dotnet_start.Controllers;

/// <summary>
/// 邮件发送控制器
/// </summary>
[SwaggerTag("邮件发送控制器")]
[ApiController]
[Route("email/send")]
public class EmailSendController(EmailSendService service) : ControllerBase
{
    /// <summary>
    /// 发送邮件
    /// </summary>
    /// <param name="from">发件人</param>
    /// <param name="to">收件人</param>
    /// <param name="subject">主题</param>
    /// <param name="message">信息</param>
    /// <returns>发送结果</returns>
    [HttpPost("text")]
    [ProducesResponseType(typeof(CommonResult<string>), StatusCodes.Status200OK)]
    public async Task<IActionResult> SendByTextPart([FromForm] string from, [FromForm] string to,
        [FromForm] string subject, [FromForm] string message)
    {
        await service.SendEmailByTextPartAsync(from, to, subject, message);
        return Ok(CommonResult<string>.Success(200, "邮件发送成功"));
    }

    /// <summary>
    /// 发送邮件-html
    /// </summary>
    /// <param name="from">发件人</param>
    /// <param name="to">收件人</param>
    /// <param name="subject">主题</param>
    /// <param name="message">信息</param>
    /// <returns>发送结果</returns>
    [HttpPost("html")]
    [ProducesResponseType(typeof(CommonResult<string>), StatusCodes.Status200OK)]
    public async Task<IActionResult> SendByHtml([FromForm] string from, [FromForm] string to,
        [FromForm] string subject, [FromForm] string message)
    {
        await service.SendEmailByHtmlAsync(from, to, subject, message);
        return Ok(CommonResult<string>.Success(200, "邮件发送成功"));
    }

    /// <summary>
    /// 发送邮件-template
    /// </summary>
    /// <param name="from">发件人</param>
    /// <param name="to">收件人</param>
    /// <param name="subject">主题</param>
    /// <param name="message">信息</param>
    /// <returns>邮件发送结果</returns>
    [HttpPost("template")]
    [ProducesResponseType(typeof(CommonResult<string>), StatusCodes.Status200OK)]
    public async Task<IActionResult> SendByHtmlTemplate([FromForm] string from, [FromForm] string to,
        [FromForm] string subject)
    {
        var dictionary = new Dictionary<string, string>
        {
            { "UserName", "菜哥" },
            { "Message", "这里是带附件的邮件 📎" }
        };
        var attachments = new List<string>
        {
            // 这里表示项目根目录下的Templates目录中的files目录中的xxxx.pdf
            Path.Combine(service.Env.ContentRootPath, "Templates", "files", "xxxx.pdf"), 
            "/xxxx/xxxx/xxx.doc" // 绝对路径，请自行更换为自己系统上文件的路径
        };

        var inlineImages = new List<string>
        {
            Path.Combine(service.Env.ContentRootPath, "Templates", "img", "vue-js.png")
        };
        await service.SendEmailByTemplateAsync(from, to, subject, "mail_template.html", dictionary, attachments, inlineImages);
        return Ok(CommonResult<string>.Success(200, "邮件发送成功"));
    }

    /// <summary>
    /// 发送邮件------表单上传文件作为内联文件或者附件文件
    /// </summary>
    /// <param name="from">发件人</param>
    /// <param name="to">收件人</param>
    /// <param name="username">用户名</param>
    /// <param name="message">邮件信息</param>
    /// <param name="subject">主题</param>
    /// <param name="attachments">附件文件</param>
    /// <param name="inlineImages">内联图片</param>
    /// <returns>结果</returns>
    [HttpPost("form")]
    [ProducesResponseType(typeof(CommonResult<string>), StatusCodes.Status200OK)]
    public async Task<IActionResult> SendByHtmlTemplateByForm(
        [FromForm] string from, [FromForm] string to, [FromForm] string username, [FromForm] string message,
        [FromForm] string subject,
        [FromForm] List<IFormFile> attachments,
        [FromForm] List<IFormFile> inlineImages
    )
    {
        var dictionary = new Dictionary<string, string>
        {
            { "UserName", username },
            { "Message", message }
        };

        await service.SendEmailByTemplateFormAsync(
            from,
            to,
            subject,
            "mail_form.html",
            dictionary,
            attachments,
            inlineImages
        );

        return Ok(CommonResult<string>.Success(200, "邮件发送成功"));
    }
}

4.自定义的临时目录与临时文件

临时目录

cs 复制代码 
namespace dotnet_start.Model;

/// <summary>
/// 自动删除的临时目录
/// </summary>
public class TempDirectory : IDisposable
{
    private readonly ILogger _logger;

    public string Path { get; }

    public TempDirectory(ILogger logger)
    {
        _logger = logger;
        Path = System.IO.Path.Combine(System.IO.Path.GetTempPath(), System.IO.Path.GetRandomFileName());
        Directory.CreateDirectory(Path);
    }

    public void Dispose()
    {
        try
        {
            if (!Directory.Exists(Path)) return;
            Directory.Delete(Path, true);
            _logger.LogDebug("删除临时目录==={Path}", Path);
        }
        catch(Exception ex)
        {
            // 忽略删除异常就直接使用 catch { }
            _logger.LogDebug(ex,"删除临时目录==={}出错了", Path);
        }
    }
}

临时文件

cs 复制代码 
namespace dotnet_start.Model;

/// <summary>
/// 自动删除的临时文件
/// </summary>
public class TempFile : IDisposable
{

    private readonly ILogger _logger;

    public string Path { get; }

    public TempFile(string directory, ILogger logger)
    {
        Path = System.IO.Path.Combine(directory, System.IO.Path.GetRandomFileName());
        _logger = logger;
    }

    public void Dispose()
    {
        try
        {
            if (!File.Exists(Path)) return;
            File.Delete(Path);
            _logger.LogDebug("删除临时文件==={Path}",Path);
        }
        catch(Exception ex)
        {
            // 忽略删除异常就直接使用 catch { }
            _logger.LogDebug(ex,"删除临时文件==={}出错了", Path);
        }
    }
}

这样使用using来定义TempDirectory或者TempFile的时候，就会自动调用Dispose方法执行删除的操作了，不需要额外手动删除了。

5.邮件发送html模板

mail_form.html

html 复制代码 
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>邮件发送模板</title>
    <style>
        body {
            font-family: "Microsoft YaHei", Arial, sans-serif;
            background-color: #f9f9f9;
            margin: 0;
            padding: 20px;
        }

        .container {
            margin: 0 auto;
            background: #fff;
            border-radius: 10px;
            padding: 20px;
            box-shadow: 0 2px 6px rgba(0, 0, 0, 0.1);
        }

        h1 {
            color: #333;
            font-size: 22px;
        }

        p {
            color: #555;
            line-height: 1.6;
        }

        .footer {
            margin-top: 30px;
            font-size: 12px;
            color: #999;
            text-align: center;
        }

        .logo {
            display: flex;
            flex-wrap: wrap;
            justify-content: center;
            gap: 10px;
            margin-bottom: 20px;
        }

        .logo img {
            cursor: pointer;
            max-width: 300px;
            max-height: 200px;
            width: auto;
            height: auto;
            object-fit: contain;
            border-radius: 8px;
            transition: transform 0.3s ease, box-shadow 0.3s ease;
        }

        .logo img:hover {
            transform: scale(1.05);
            box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
        }

    </style>
</head>
<body>
<div class="container">
    <div class="logo">
        {{InlineImages}}
    </div>
    <h1>您好，{{UserName}} 👋</h1>
    <p>{{Message}}</p>


    <div class="footer">
        <p>这是一封系统自动发送的邮件，请勿直接回复。</p>
    </div>
</div>
</body>
</html>

mail_template.html

html 复制代码 
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>邮件发送模板</title>
    <style>
        body {
            font-family: "Microsoft YaHei", Arial, sans-serif;
            background-color: #f9f9f9;
            margin: 0;
            padding: 20px;
        }
        .container {
            max-width: 600px;
            margin: 0 auto;
            background: #fff;
            border-radius: 10px;
            padding: 20px;
            box-shadow: 0 2px 6px rgba(0,0,0,0.1);
        }
        h1 {
            color: #333;
            font-size: 22px;
        }
        p {
            color: #555;
            line-height: 1.6;
        }
        .footer {
            margin-top: 30px;
            font-size: 12px;
            color: #999;
            text-align: center;
        }
        .logo {
            text-align: center;
            margin-bottom: 20px;
        }
        .logo img {
            max-width: 300px;
            max-height: 200px;
        }
    </style>
</head>
<body>
<div class="container">
    <div class="logo">
        <img src="cid:vue-js" alt="vue"/>
    </div>
    <h1>您好，{{UserName}} 👋</h1>
    <p>{{Message}}</p>

    <div class="footer">
        <p>这是一封系统自动发送的邮件，请勿直接回复。</p>
    </div>
</div>
</body>
</html>

6.QQ邮箱开启SMTP页面

7.使用apifox测试邮件发送

到此，邮件发送功能完成，大家可以拷贝粘贴代码自行尝试即可。

相关推荐
王嘉俊92510 小时前
Flask 入门：轻量级 Python Web 框架的快速上手
开发语言·前端·后端·python·flask·入门
yeyong10 小时前
没有arm64 cpu， 在本地amd64环境上如何制作arm64架构下可用的镜像
后端
做运维的阿瑞11 小时前
Python 面向对象编程深度指南
开发语言·数据结构·后端·python
RoyLin11 小时前
V8引擎与VM模块
前端·后端·node.js
yinke小琪11 小时前
凌晨2点，我删光了所有“精通多线程”的代码
java·后端·面试
Cherry Zack11 小时前
Django 视图与路由基础：从URL映射到视图函数
后端·python·django
Leinwin11 小时前
Codex CLI 配置 Azure OpenAI GPT-5-codex 指南
后端·python·flask
会跑的葫芦怪11 小时前
Go test 命令完整指南：从基础到高级用法
开发语言·后端·golang
大飞pkz12 小时前
【设计模式】代理模式
开发语言·设计模式·c#·代理模式
Cache技术分享12 小时前
203. Java 异常 - Throwable 类及其子类
前端·后端
热门推荐
01OpenSpeedy简介02在国行 macOS 下用 DeepSeek 补齐 Xcode 26 的 AI 能力：问题、原因与 mitmproxy 解决方案（含可用脚本与安装教程）03UV安装并设置国内源04GitHub 镜像站点05UV 工具安装与国内镜像源配置指南06KGG转MP3工具|非KGM文件|解密音频07阿里最新开源Wan2.2-Animate-14B 本地部署教程：统一双模态框架，MoE架构赋能电影级角色动画与替换08VsCode远程Copilot无法使用Claude Agent问题09Spec-Kit 使用指南1046个Nano-banana 精选提示词，持续更新中