如何获取自定义域名邮箱的SMTP主机名与端口号以实现应用发信

Great question! When you're working with custom domain email accounts and need to set up email sending in your app, here's how to track down the right SMTP host and port, plus a solid example using Gmail to tie it all together:

• Check your provider's documentation: Most email hosting services (like Google Workspace, Outlook 365, or cPanel-based hosts) clearly list their SMTP settings in admin dashboards or help sections. Look for terms like "outgoing mail server" or "SMTP server details".
• Use DNS record checks: You can look up your domain's MX records (for mail routing) or SRV records (some providers publish these specifically for SMTP). For common setups:
  • Google Workspace custom domains use the same SMTP as regular Gmail: smtp.gmail.com with port 587 (TLS) or 465 (SSL).
  • cPanel-hosted emails typically use mail.yourdomain.com with ports 587 (TLS) or 465 (SSL).
• Reach out to support: If you're stuck, your email hosting provider's support team will give you the exact, up-to-date settings—this is the most reliable route.

Here's a corrected, complete code snippet (fixed the typo in mailMessage from your original example) to send an email using Gmail's SMTP server:

using System.Net;
using System.Net.Mail;

// Build the email message
MailMessage mailMessage = new MailMessage();
mailMessage.From = new MailAddress("from@gmail.com");
mailMessage.Subject = "Test Email";
mailMessage.IsBodyHtml = true;
mailMessage.Body = "<h1>This is a test HTML email</h1>";
mailMessage.To.Add("recipient@example.com");

// Configure the SMTP client
SmtpClient smtpClient = new SmtpClient("smtp.gmail.com", 587);
// For 2FA-enabled accounts, use an App Password instead of your regular password
smtpClient.Credentials = new NetworkCredential("from@gmail.com", "your-app-password-here");
smtpClient.EnableSsl = true;

try
{
    smtpClient.Send(mailMessage);
    Console.WriteLine("Email sent successfully!");
}
catch (Exception ex)
{
    Console.WriteLine($"Oops, something went wrong: {ex.Message}");
}
finally
{
    // Clean up resources
    smtpClient.Dispose();
    mailMessage.Dispose();
}

Key Notes for Gmail Users:

• If you have two-factor authentication (2FA) enabled on your Gmail account, you can't use your regular password here. Instead, create an App Password in your Google Account's Security settings.
• "Less secure app access" is no longer supported, so app passwords are the only valid way to authenticate with Gmail's SMTP when 2FA is on.

内容的提问来源于stack exchange，提问作者Srujan Chowdary Panda