GetMessageCount() returns 0 (zero)

问题

public class _Variable
{
    public bool MailStat;
    public Pop3Client pop3;
    public int lastmailCount;
    public int currentmailCount;
    public Message msg;
    public MessagePart msgPart;
    public Timer _timer;        
}

public List<int> _MailReader()
{
    _Variable _var = new _Variable();
    try
    {
        //HttpContext.Current.Session["Pop3Client"]

        if (HttpContext.Current.Session["Pop3Client"] == null)
        {
            _var.pop3 = new Pop3Client();
            _var.pop3.Connect("pop.gmail.com", 995, true);
            _var.MailStat = _var.pop3.Connected;
            _var.pop3.Authenticate("nithin.testing1@gmail.com", "xxxxxxx");
            HttpContext.Current.Session["Pop3Client"] = _var.pop3;
        }
        else
        {
            _var.pop3 = (Pop3Client)HttpContext.Current.Session["Pop3Client"];
        }
        if (_var.MailStat)
        {

            //HttpContext.Current.Application["lastmailCount"] = _var.pop3.GetMessageCount();
            _var.currentmailCount = _var.pop3.GetMessageCount();
            _var.lastmailCount = _global.lastmailCount;
            if (_var.lastmailCount < _var.currentmailCount)
            {
                _global.lastmailCount = _var.currentmailCount;
                int _diff = _var.currentmailCount - _var.lastmailCount;
                for (int _loop = _var.currentmailCount; _diff > 0; _diff--)
                {
                    _var.msg = _var.pop3.GetMessage(_loop-(_diff-1));
                    _var.msgPart = _var.msg.MessagePart.MessageParts[0];
                    string bodyPart = _var.msgPart.BodyEncoding.GetString(_var.msgPart.Body).ToString().Trim();
                    int _result;
                    if (int.TryParse(bodyPart, out _result))
                    {
                        _global._vbill.Add(Int32.Parse(bodyPart));
                        _global._vDate.Add(_var.msg.Headers.DateSent.ToString());
                    }
                }
            }
        }
        _var.pop3.Dispose();
        return _global._vbill;
    }
    catch (Exception ex)
    {
        return _global._vbill;
    }
}

I am using the OpenPop.dll and In the following code pop.getMessageCount is returning zero even there are mails in my account.

_Variable method contains all the variables I used in the code and in _MailReader. I am just reading all my mails from my application and returning into a list but this is the problem count is zero always.

回答1:

It's a feature of gmail pop3 server. By default, you can receive only unread messages. That means, if you or somebody else already has downloaded certain message once, it will not be possible to receive it by pop3 protocol anymore.

To avoid it, you have to configure your gmail account. Check "Enable POP for all mail (event mail that's already been downloaded)" in "Forwarding and POP/IMAP" section of gmail settings.

Screenshot: http://i.stack.imgur.com/UE7ip.png

来源：https://stackoverflow.com/questions/11284946/getmessagecount-returns-0-zero

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ASP.NET

gmail

openpop