title: ASP.NET MVC Blog Project Email Service Error: ArgumentNullException: Value cannot be null. (Parameter 'host')
body: <blockquote>
  <p>ArgumentNullException: Value cannot be null. (Parameter 'host')</p>
  </blockquote>
  <p>I keep getting this error no matter what I do outside of trying to log in it'll give me invalid login attempts and it tells me some usernames are already taken when I try to re-register a user but when I register the user initially it'll give me the null exception.</p>
  <pre><code>public async Task SendEmailAsync(string emailTo, string subject, string htmlMessage)
  {
          var email = new MimeMessage();
  
          email.Sender = MailboxAddress.Parse(_mailSettings.Mail);
          email.To.Add(MailboxAddress.Parse(emailTo));
          email.Subject = subject;
  
          var builder = new BodyBuilder()
          {
              HtmlBody = htmlMessage
          };
  
          email.Body = builder.ToMessageBody();
  
          using var smtp = new SmtpClient();
          smtp.Connect(_mailSettings.Host, _mailSettings.Port, SecureSocketOptions.StartTls);
          smtp.Authenticate(_mailSettings.Mail, _mailSettings.Password);
  
          await smtp.SendAsync(email);
  
          smtp.Disconnect(true);
  }
  </code></pre>