MailKit.Net.Smtp.SmtpClient.Authenticate C# (CSharp) Method

		public override void Authenticate (Encoding encoding, ICredentials credentials, CancellationToken cancellationToken = default (CancellationToken))
		{
			if (encoding == null)
				throw new ArgumentNullException (nameof (encoding));

			if (credentials == null)
				throw new ArgumentNullException (nameof (credentials));

			CheckDisposed ();

			if (!IsConnected)
				throw new ServiceNotConnectedException ("The SmtpClient must be connected before you can authenticate.");

			if (IsAuthenticated)
				throw new InvalidOperationException ("The SmtpClient is already authenticated.");

			if ((capabilities & SmtpCapabilities.Authentication) == 0)
				throw new NotSupportedException ("The SMTP server does not support authentication.");

			var uri = new Uri ("smtp://" + host);
			AuthenticationException authException = null;
			SmtpResponse response;
			SaslMechanism sasl;
			bool tried = false;
			string challenge;
			string command;

			foreach (var authmech in SaslMechanism.AuthMechanismRank) {
				if (!AuthenticationMechanisms.Contains (authmech))
					continue;

				if ((sasl = SaslMechanism.Create (authmech, uri, encoding, credentials)) == null)
					continue;

				tried = true;

				cancellationToken.ThrowIfCancellationRequested ();

				// send an initial challenge if the mechanism supports it
				if (sasl.SupportsInitialResponse) {
					challenge = sasl.Challenge (null);
					command = string.Format ("AUTH {0} {1}", authmech, challenge);
				} else {
					command = string.Format ("AUTH {0}", authmech);
				}

				response = SendCommand (command, cancellationToken);

				if (response.StatusCode == SmtpStatusCode.AuthenticationMechanismTooWeak)
					continue;

				SaslException saslException = null;

				try {
					while (!sasl.IsAuthenticated) {
						if (response.StatusCode != SmtpStatusCode.AuthenticationChallenge)
							throw new SmtpCommandException (SmtpErrorCode.UnexpectedStatusCode, response.StatusCode, response.Response);

						challenge = sasl.Challenge (response.Response);
						response = SendCommand (challenge, cancellationToken);
					}

					saslException = null;
				} catch (SaslException ex) {
					// reset the authentication state
					response = SendCommand (string.Empty, cancellationToken);
					saslException = ex;
				}

				if (response.StatusCode == SmtpStatusCode.AuthenticationSuccessful) {
					if (QueryCapabilitiesAfterAuthenticating)
						Ehlo (cancellationToken);
					authenticated = true;
					OnAuthenticated (response.Response);
					return;
				}

				var message = string.Format ("{0}: {1}", response.StatusCode, response.Response);

				if (saslException != null)
					authException = new AuthenticationException (message, saslException);
				else
					authException = new AuthenticationException (message);
			}

			if (tried)
				throw authException ?? new AuthenticationException ();

			throw new NotSupportedException ("No compatible authentication mechanisms found.");
		}

        public void Send(EmailDependencies email)
        {
            try
            {
                var message = new MimeMessage();
                message.From.Add(new MailboxAddress(email.FromName, email.FromAddress));

                message.To.Add(new MailboxAddress(email.ToName, email.ToAddress));
                message.To.Add(new MailboxAddress(email.FromName, email.FromAddress));

                message.Subject = email.Title;
                message.Body = new TextPart("html") { Text = email.content };

                using (var client = new SmtpClient())
                {
                    client.Connect("mail.bizmonger.net", 587, 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
                    client.Authenticate(Configuration.ServerEmail, Configuration.Password);

                    client.Send(message);
                    client.Disconnect(true);
                }
            }
            catch (Exception ex)
            {
                var errorMessage = ex.GetBaseException().Message;
                Debug.WriteLine(errorMessage);
            }
        }