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XMail Forum > Documentation and Knowledge Base > Simultaneous Multi-user Access To Pop3?

Posted by: olaf Jul 31 2007, 02:47 PM

Hi, guys!

Is there any ability to get simultaneous multi-user access to single POP3 mailbox?

I have digged the XMail Handbook, XMail documentation, whole forum and run through mailing list archive - and found nothing about this option.

Thanks for your help!

I'm looking forward to your reply.

/Olaf

Posted by: hschneider Jul 31 2007, 02:54 PM

No - the POP3 protocol is designed for a single session, therefore the POP box will be logged by the first login.

Why do you need multi-user access ?

Posted by: olaf Aug 1 2007, 07:53 AM

All of most usable mail-servers allow this feature by default, and there are no POP3 protocol restrictions.

Are there other reasons to disable this option by default? I assume that is something connected with the locking mechanism of XMail.

Why this option is necessary - it is simple: some of clients using shared mailboxes, for example - support, sales, etc. These mailboxes must be accessible simultaneously in any time with no restrictions at all.

Another reason - usage of some kind of mail dispatchers with 3rd party mail clients. For example - I've used TheBAT! mail client at work and one of usable mailbox access options - call of remote mail dispatcher for chosen mailbox. At the same time I've used my PDA to access to the same mailbox, but TheBAT! waits for my reaction and keeps POP3 session in open state. By result - I can't access my mailbox from any place while TheBAT! binds the POP3 channel with the dispatcher.

The only problem why I can't migrate to XMail from my current QMAIL installation - is the absence of simultaneous multi-user access to POP3 mailboxes.

Thanks for feedback! I'll wait for your answer.

Posted by: hschneider Aug 1 2007, 10:57 AM

I see .. the problem: It is not an option, but obviously needed by XMail's internal session handler. The reasons you have listed above are clear and useful and XMail should support this too. Pls post a feature request directly to Davidel at xmailserver.org. I'll post that to the developer forum too. - Thanks!

Posted by: hschneider Aug 1 2007, 12:47 PM

> ... and there are no POP3 protocol restrictions.

There are - this is how POP3 is defined in RFC1939:

QUOTE

Once the POP3 server has determined through the use of any
   authentication command that the client should be given access to the
   appropriate maildrop, the POP3 server then acquires an exclusive-
   access lock on the maildrop, as necessary to prevent messages from
   being modified or removed before the session enters the UPDATE state.
   If the lock is successfully acquired, the POP3 server responds with a
   positive status indicator. The POP3 session now enters the
   TRANSACTION state, with no messages marked as deleted. If the
   maildrop cannot be opened for some reason (for example, a lock can
   not be acquired, the client is denied access to the appropriate

However, I share your opinion. Let's wait for Davide's response.

Posted by: olaf Aug 1 2007, 01:10 PM

Thanks for your time, attention and help!
I'll follow your suggestion and will write to David.

Thanks.

/Olaf

Posted by: olaf Aug 3 2007, 11:59 AM

And I've got no reply from Davide...

Is that normal?

/Oalf

Posted by: hschneider Aug 3 2007, 02:34 PM

Looks like he is offline for a couple of days.

Posted by: olaf Aug 10 2007, 07:48 AM

After some digging in the code of XMail I have found goal lock blocking this ability in the POP3Utils.cpp file:

Here is necessary to comment a part of code to remove mailbox locking block to get simultaneous multi-user access to POP3 mailbox:

/*
if (UsrPOP3Lock(pUI) < 0) {
printf ("UsrPOP3Lock: %d \n", UsrPOP3Lock(pUI));
UsrFreeUserInfo(pUI);
return INVALID_POP3_HANDLE;
}
*/

Other functions are work perfectly.

Thanks for the attention.

/Oleg

P.S. Davide is still keeps silence.

Posted by: olaf Aug 10 2007, 07:52 AM

UPopBuildSession function, I forgot to mention about it...

/Oleg

Posted by: hschneider Aug 10 2007, 03:33 PM

THANX !

Posted by: olaf Aug 15 2007, 11:37 AM

Another thing, that is really necessary to correct RETR mechanism!

The problem is: while the some of users are delete some of messages (e.g. - spam messages), other users connected to this mailbox are impossible to get whole batch of messages, because XMail returns wrong answer for the deleted messages

retr 4
+OK 720 bytes

while the message is really deleted. Mail client got this answer and waits for content of the message. In the same time, the TOP command returns correct "-ERR" value (could not open file).

To correct this issue we need to find UPopSessionSendMsg function in the POP3Utils.cpp file and past "check the existence of the file" block of code before the line

char szResponse[256] = "";

The inserted part of code for this check looks like this:

FILE *pMsgFile = fopen(szMsgFilePath, "rb");
if (pMsgFile == NULL) {
UPopSendErrorResponse(hBSock, ERR_FILE_OPEN, pPOPSD->iTimeout);

ErrSetErrorCode(ERR_FILE_OPEN);
return ERR_FILE_OPEN;
}
fclose(pMsgFile);

---Thanks for your attention
/Olaf

Posted by: hschneider Aug 16 2007, 05:42 PM

Thanks for the patchwork !

Posted by: NomadCF Aug 17 2007, 12:00 AM

With out trying being rude this "option / idea" your speaking of is really what IMAP excels at. POP3 was never designed to allow multi users to 1 mailbox. Nor can I think out a email server that does handle this "option / idea" well if at all and I've tried it xmail, exchnage, and lotus domino.

Dovecot handled it the best but still had issues with a email that was deleted at the same time a user was getting it.

And while the patch you prodived helps was still able to have xmail have issue it the email was gotten/deleted at the exact same time.

Yet I could deleted the message and try to open it at the exact same time with a imap server (both dovecot and lotus domino's imap).