Asp.Net Core 3 ssl发送邮件失败,解决方案:第三方组件Mailkit

1.博客园有提到：https://www.cnblogs.com/tsql/p/9078163.html   ，这个是 .Net Freamwork的解决方案 ，当切换成core的情况 ，利用System.web.mail发送邮件方法不行（在core下面System.web这个命名空间类全部移除，若切换NetFreamwork到core代码也是重点切换内容）。

2.虽然 core下面 System.net.mail  是有的，但是和 .Net Freamwork版本同样的问题，ssl发送邮件失败。

3.最终采取方法是采用第三方组件Mailkit ， 具体代码如下：

nuget 添加 ：MailKit

using MailKit;

public static bool SendEmail(EmailAccount emailAccount, string toAddress, string subject, string body)
{
	var mailAddress = emailAccount.MailAddress;
	var message = new MimeMessage();
	message.From.Add(new MailboxAddress(mailAddress));
	foreach (var to in toAddress.Split(','))
	{
		message.To.Add(new MailboxAddress(to));
	}
	message.Subject = subject;
	message.Body = new TextPart(MimeKit.Text.TextFormat.Html) { Text = body };
	
	using (var client = new SmtpClient())
	{
		// For demo-purposes, accept all SSL certificates (in case the server supports STARTTLS)
		client.ServerCertificateValidationCallback = (s, c, h, e) => true;

		client.Connect(emailAccount.Host, emailAccount.Port, emailAccount.EnableSsl);

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

		// Note: only needed if the SMTP server requires authentication
		client.Authenticate(mailAddress, emailAccount.Password);

		client.Send(message);
		client.Disconnect(true);
	}
	return true;
}