我正在使用ASP.NET Core并使用MailKit来实现电子邮件功能。我之前使用的方法已不再适用。
我有一个SmtpOptions.cs类：
public class SmtpOptions
{
public string Server { get; set; } = "smtp.gmail.com"; //Gmail limited to 2000 emails per day
public int Port { get; set; } = 465; //default for SSL using GMail
public string User { get; set; } = "[email protected]"; //must match server domain
public string Password { get; set; } = "myPwd";
public bool UseSsl { get; set; } = true; //gmail requires SSL
public bool RequiresAuthentication { get; set; } = true; //gmail requires authentication
public string PreferredEncoding { get; set; } = string.Empty;
}
和EmailSender.cs类：
public class EmailSender
{
public EmailSender()
{
}
public async Task SendEmailAsync(
SmtpOptions smtpOptions,
string to,
string from,
string subject,
string plainTextMessage,
string htmlMessage,
string replyTo = null)
{
if (string.IsNullOrWhiteSpace(to))
{
throw new ArgumentException("no to address provided");
}
if (string.IsNullOrWhiteSpace(from))
{
throw new ArgumentException("no from address provided");
}
if (string.IsNullOrWhiteSpace(subject))
{
throw new ArgumentException("no subject provided");
}
var hasPlainText = !string.IsNullOrWhiteSpace(plainTextMessage);
var hasHtml = !string.IsNullOrWhiteSpace(htmlMessage);
if (!hasPlainText && !hasHtml)
{
throw new ArgumentException("no message provided");
}
var m = new MimeMessage();
m.From.Add(new MailboxAddress("", from));
if (!string.IsNullOrWhiteSpace(replyTo))
{
m.ReplyTo.Add(new MailboxAddress("", replyTo));
}
m.To.Add(new MailboxAddress("", to));
m.Subject = subject;
//m.Importance = MessageImportance.Normal;
//Header h = new Header(HeaderId.Precedence, "Bulk");
//m.Headers.Add()
BodyBuilder bodyBuilder = new BodyBuilder();
if (hasPlainText)
{
bodyBuilder.TextBody = plainTextMessage;
}
if (hasHtml)
{
bodyBuilder.HtmlBody = htmlMessage;
}
m.Body = bodyBuilder.ToMessageBody();
using (var client = new SmtpClient())
{
await client.ConnectAsync(
smtpOptions.Server,
smtpOptions.Port,
smtpOptions.UseSsl)
.ConfigureAwait(false);
// 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
if (smtpOptions.RequiresAuthentication)
{
await client.AuthenticateAsync(smtpOptions.User, smtpOptions.Password)
.ConfigureAwait(false);
}
await client.SendAsync(m).ConfigureAwait(false);
await client.DisconnectAsync(true).ConfigureAwait(false);
}
}
public async Task SendMultipleEmailAsync(
SmtpOptions smtpOptions,
string toCsv,
string from,
string subject,
string plainTextMessage,
string htmlMessage)
{
if (string.IsNullOrWhiteSpace(toCsv))
{
throw new ArgumentException("no to addresses provided");
}
if (string.IsNullOrWhiteSpace(from))
{
throw new ArgumentException("no from address provided");
}
if (string.IsNullOrWhiteSpace(subject))
{
throw new ArgumentException("no subject provided");
}
var hasPlainText = !string.IsNullOrWhiteSpace(plainTextMessage);
var hasHtml = !string.IsNullOrWhiteSpace(htmlMessage);
if (!hasPlainText && !hasHtml)
{
throw new ArgumentException("no message provided");
}
var m = new MimeMessage();
m.From.Add(new MailboxAddress("", from));
string[] adrs = toCsv.Split(',');
foreach (string item in adrs)
{
if (!string.IsNullOrEmpty(item)) { m.To.Add(new MailboxAddress("", item)); ; }
}
m.Subject = subject;
m.Importance = MessageImportance.High;
BodyBuilder bodyBuilder = new BodyBuilder();
if (hasPlainText)
{
bodyBuilder.TextBody = plainTextMessage;
}
if (hasHtml)
{
bodyBuilder.HtmlBody = htmlMessage;
}
m.Body = bodyBuilder.ToMessageBody();
using (var client = new SmtpClient())
{
await client.ConnectAsync(
smtpOptions.Server,
smtpOptions.Port,
smtpOptions.UseSsl).ConfigureAwait(false);
// 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
if (smtpOptions.RequiresAuthentication)
{
await client.AuthenticateAsync(
smtpOptions.User,
smtpOptions.Password).ConfigureAwait(false);
}
await client.SendAsync(m).ConfigureAwait(false);
await client.DisconnectAsync(true).ConfigureAwait(false);
}
}
}
用于函数调用：
public async void ContactMessage(string title, string message, string toEmail)
{
string thisMessage = "No Message Provided";
if (!String.IsNullOrEmpty(message)) { thisMessage = message; } //in case empty form
string thisTitle = title;
//create email objects
EmailSender emailSender = new EmailSender();
SmtpOptions smtpOptions = new SmtpOptions(); //default settings ok
string fromEmail = smtpOptions.User;
string subjectLine = "Message Title";
await emailSender.SendEmailAsync(smtpOptions, toEmail, fromEmail, subjectLine, thisMessage, "");
}
如上所述，此方法之前已经有效，但现在我的Gmail无法响应。我已经检查并启用了IMAP和POP。
特定的异常读取：“System.Net.Internals.SocketExceptionFactory.ExtendedSocketE xception：'连接尝试失败，因为连接方在一段时间后没有正确响应，或者建立的连接失败，因为连接的主机未能响应'”
此代码尚未部署，但会在测试环境中导致此错误。移动到不同的防火墙系统会导致错误“Mailkit.Security.Authentication; MailKit身份验证太弱”
使用Yahoo!进行测试smtp允许上面的代码工作，所以看起来Mailkit和Gmail之间的兼容性已经改变。使用Gmail的相应Mailkit配置是什么？
通常，当您收到AuthenticationException表示AUTH机制太弱时，这意味着客户端尝试使用PLAIN或LOGIN机制，并且服务器仅允许通过SSL使用这些机制。
确保在启用SSL的端口465上连接，或在端口587上连接SecureSocketOptions.StartTls作为第三个参数。
电子邮件帐户设置未配置为允许使用安全性较低的应用。这两种解决方案是：
1）在EmailSender.cs类中获取OAuth 2.0凭据，或2）更改电子邮件帐户设置以允许不太安全的应用程序