IMAP and POP3 Clients in C#

using System;
using System.Collections.Generic;
using System.Text;

namespace LumiSoft.Net.SMTP.Server
{
    /// <summary>
    /// This class holds MAIL FROM: command value.
    /// </summary>
    public class SMTP_MailFrom
    {
        private string       m_Mailbox = "";
        private int          m_Size    = -1;
        private string       m_Body    = null;
        private SMTP_DSN_Ret m_RET     = SMTP_DSN_Ret.NotSpecified;
        private string       m_ENVID   = null;

        /// <summary>
        /// Default constructor.
        /// </summary>
        /// <param name="mailbox">Mailbox value.</param>
        /// <param name="size">SIZE parameter value.</param>
        /// <param name="body">BODY parameter value.</param>
        /// <param name="ret">DSN RET parameter value.</param>
        /// <param name="envid">DSN ENVID parameter value.</param>
        /// <exception cref="ArgumentNullException">Is raised when <b>mailbox</b> is null reference.</exception>
        public SMTP_MailFrom(string mailbox,int size,string body,SMTP_DSN_Ret ret,string envid)
        {
            if(mailbox == null){
                throw new ArgumentNullException("mailbox");
            }

            m_Mailbox = mailbox;
            m_Size    = size;
            m_Body    = body;
            m_RET     = ret;
            m_ENVID   = envid;
        }


        #region Properties implementation

        /// <summary>
        /// Gets SMTP "mailbox" value. Actually this is just email address.
        /// This value can be "" if "null reverse-path".
        /// </summary>
        public string Mailbox
        {
            get{ return m_Mailbox; }
        }

        /// <summary>
        /// Gets MAIL FROM: SIZE parameter value. Value -1 means not specified.
        /// Defined in RFC 1870.
        /// </summary>
        public int Size
        {
            get{ return m_Size; }
        }

        /// <summary>
        /// Gets MAIL FROM: BODY parameter value. Value null means not specified.
        /// Defined in RFC 1652.
        /// </summary>
        public string Body
        {
            get{ return m_Body; }
        }

        /// <summary>
        /// Gets DSN RET parameter value. Value null means not specified.
        /// RET specifies whether message or headers should be included in any failed DSN issued for message transmission.
        /// Defined in RFC 1891.
        /// </summary>
        public SMTP_DSN_Ret RET
        {
            get{ return m_RET; }
        }

        /// <summary>
        /// Gets DSN ENVID parameter value. Value null means not specified.
        /// Defined in RFC 1891.
        /// </summary>
        public string ENVID
        {
            get{ return m_ENVID; }
        }

        #endregion
    }
}