SendGrid.Net.Mail.MailAddress.ParseAddress C# (CSharp) Method

        void ParseAddress(string address)
        {
            // 1. Quotes for display name
            address = address.Trim();
            int idx = address.IndexOf('"');
            if (idx != -1)
            {
                if (idx != 0 || address.Length == 1)
                    throw CreateFormatException();

                int closing = address.LastIndexOf('"');
                if (closing == idx)
                    throw CreateFormatException();

                if (this.DisplayName == null)
                    this.DisplayName = address.Substring(idx + 1, closing - idx - 1).Trim();
                address = address.Substring(closing + 1).Trim();
            }

            // 2. <email>
            idx = address.IndexOf('<');
            if (idx >= 0)
            {
                if (this.DisplayName == null)
                    this.DisplayName = address.Substring(0, idx).Trim();
                if (address.Length - 1 == idx)
                    throw CreateFormatException();

                int end = address.IndexOf('>', idx + 1);
                if (end == -1)
                    throw CreateFormatException();

                address = address.Substring(idx + 1, end - idx - 1).Trim();
            }
            this.Address = address;
            // 3. email
            idx = address.IndexOf('@');
            if (idx <= 0)
                throw CreateFormatException();
            if (idx != address.LastIndexOf('@'))
                throw CreateFormatException();

            this.User = address.Substring(0, idx).Trim();
            if (User.Length == 0)
                throw CreateFormatException();
            this.Host = address.Substring(idx + 1).Trim();
            if (Host.Length == 0)
                throw CreateFormatException();
        }