1. 安装Microsoft.Extensions.Options和Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation NuGet软件包。
2. 配置电子邮件服务器设置，例如，在appsettings.json文件中添加以下内容：

"EmailSettings": {
    "EmailAddress": "youremail@example.com",
    "Password": "yourpassword",
    "SMTPHost": "smtp.yourdomain.com",
    "SMTPPort": 587,
    "SSL": true
}

3. 在开始.cs文件中注册IOptions和SmtpOptions：

services.Configure(Configuration.GetSection("EmailSettings"));

4. 在控制器中注入IOptions：

private readonly IOptions _smtpOptions;
public EmailController(IOptions smtpOptions)
{
    _smtpOptions = smtpOptions;
}

5. 在控制器中添加发送电子邮件的方法，例如：

public async Task SendEmail(string emailTo, string subject, string message)
{
    var emailMessage = new MimeMessage();

    emailMessage.From.Add(new MailboxAddress(_smtpOptions.Value.EmailAddress));
    emailMessage.To.Add(new MailboxAddress(emailTo));
    emailMessage.Subject = subject;

    var emailBody = new BodyBuilder { HtmlBody = message };

    emailMessage.Body = emailBody.ToMessageBody();

    using var client = new SmtpClient();
    await client.ConnectAsync(_smtpOptions.Value.SMTPHost, _smtpOptions.Value.SMTPPort, _smtpOptions.Value.SSL);
    await client.AuthenticateAsync(_smtpOptions.Value.EmailAddress, _smtpOptions.Value.Password);
    await client.SendAsync(emailMessage);
    await client.DisconnectAsync(true);
}

6. 在Razor视图中，您可以调用该方法并传递电子邮件、主题和消息参数，例如：

@{
    await SendEmail("recipient@example.com", "Hello from ASP.NET Core 5.0 Razor", "
Hello World
This is a test email from ASP.NET Core 5.0 Razor
");
}