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

		void Ehlo (CancellationToken cancellationToken)
		{
			SmtpResponse response;

			response = SendEhlo (true, cancellationToken);

			// Some SMTP servers do not accept an EHLO after authentication (despite the rfc saying it is required).
			if (authenticated && response.StatusCode == SmtpStatusCode.BadCommandSequence)
				return;

			if (response.StatusCode != SmtpStatusCode.Ok) {
				// Try sending HELO instead...
				response = SendEhlo (false, cancellationToken);
				if (response.StatusCode != SmtpStatusCode.Ok)
					throw new SmtpCommandException (SmtpErrorCode.UnexpectedStatusCode, response.StatusCode, response.Response);
			} else {
				// Clear the extensions
				capabilities = SmtpCapabilities.None;
				AuthenticationMechanisms.Clear ();
				MaxSize = 0;

				var lines = response.Response.Split ('\n');
				for (int i = 0; i < lines.Length; i++) {
					// Outlook.com replies with "250-8bitmime" instead of "250-8BITMIME"
					// (strangely, it correctly capitalizes all other extensions...)
					var capability = lines[i].Trim ().ToUpperInvariant ();

					if (capability.StartsWith ("AUTH", StringComparison.Ordinal)) {
						int index = 4;

						capabilities |= SmtpCapabilities.Authentication;

						if (index < capability.Length && capability[index] == '=')
							index++;

						var mechanisms = capability.Substring (index);
						foreach (var mechanism in mechanisms.Split (new [] { ' ' }, StringSplitOptions.RemoveEmptyEntries))
							AuthenticationMechanisms.Add (mechanism);
					} else if (capability.StartsWith ("SIZE", StringComparison.Ordinal)) {
						int index = 4;
						uint size;

						capabilities |= SmtpCapabilities.Size;

						while (index < capability.Length && char.IsWhiteSpace (capability[index]))
							index++;

						if (uint.TryParse (capability.Substring (index), out size))
							MaxSize = size;
					} else if (capability == "DSN") {
						capabilities |= SmtpCapabilities.Dsn;
					} else if (capability == "BINARYMIME") {
						capabilities |= SmtpCapabilities.BinaryMime;
					} else if (capability == "CHUNKING") {
						capabilities |= SmtpCapabilities.Chunking;
					} else if (capability == "ENHANCEDSTATUSCODES") {
						capabilities |= SmtpCapabilities.EnhancedStatusCodes;
					} else if (capability == "8BITMIME") {
						capabilities |= SmtpCapabilities.EightBitMime;
					} else if (capability == "PIPELINING") {
						capabilities |= SmtpCapabilities.Pipelining;
					} else if (capability == "STARTTLS") {
						capabilities |= SmtpCapabilities.StartTLS;
					} else if (capability == "SMTPUTF8") {
						capabilities |= SmtpCapabilities.UTF8;
					}
				}
			}
		}