Error: "Error logging off from server: Object reference not set to an instance"

[zxdavb]

Hi, I am running PopGrabber v1.09 free edition on Exchange 2010 on Windows 2008 Std R2.  I note previous emails saying that Exchange 2010 wont be supported until it is released, but I understand it is now released.

Anyway, I get an error message: "Error logging off from server: Object reference not set to an instance".  

I am prettry sure both the exchange server and PopGrabber are configured correctly, as I am successfuly using another product, but one which will expire in a few days (i.e. evaluation software)...

I note the following KB article from MS, but neither of the two files exist on my server: http://support.microsoft.com/kb/810098

I am hoping that you have an easy answer for this.  Thanks in advance.

The relevant portion of the log file (in debug? mode) is:

Code:

2009-09-17T10:14:40: PopGrabber accounts refresh command received
2009-09-17T10:14:43: 1 accounts loaded
2009-09-17T10:14:43: Manual download started
2009-09-17T10:14:43: Starting POP3 Download for 1 accounts.
2009-09-17T10:14:43: Processing account john@john.smith.name on server pop3.john.smith.name
2009-09-17T10:14:43: Establishing POP3 connection to pop3.john.smith.name on port 110
2009-09-17T10:14:44: Logging in to POP3 Server
2009-09-17T10:14:44: Retrieving message count
2009-09-17T10:14:44: 1 message(s) on server
2009-09-17T10:14:44: Retrieving message 1
2009-09-17T10:14:51: Message 1 succesfully downloaded
2009-09-17T10:14:51: Connecting to SMTP Server mail.smithfamily.local on port 25
2009-09-17T10:14:52: Error connecting to SMTP Server (mail.smithfamily.local): Error logging off from server: Object reference not set to an instance of an object.
2009-09-17T10:14:52: Finished Processing 1 accounts.
2009-09-17T10:15:07: PopGrabber accounts refresh command received

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[Eclarsys Support]

Hello,

it seems PopGrabber is having problems connecting to the SMTP server. Do you see any message from the Exchange SMTP virtual server?

Please check the windows application event log in the Exchange server.

One more thing: open a cmd window and execute "telnet mail.smithfamily.local 25". Do you get a connection to the server?

Also try using an IP address instead of the hostname and tell us if this works.

Regards,

Eclarsys Support

[zxdavb]

Thanks, the work-around you suggested fixed the problem (i.e. "try using an IP address instead of the hostname").

Specifically, changing the SMTP server from the DNS hostname to the IP4 address solved the problem, regardless of wether I used the actual address (172.27.0.200) or the loopback address (127.0.0.1).  However, this is odd, because name resolution (using ping as well as nslookup) resolves the hostname to the correct address, _as long as_ I force it to use IP4 (with the -4 switch in the case of ping) - it seems the GetHostByName API returns an IP6 address by default.  

I can assure you that there was/is no problem with name resolution (i.e. I get the right addresses for the hostname, which itself it the correct smtp server name).  BTW, I didn't test it with telnet, but the other POP3-SMTP gateway worked OK using the same hostname.

So it seems to be that using an IP6 address with some .NET provider causes the issue?  

To test the idea, I would like to try removing IP6 altogether and seeing what happens with the hostname, or using an IP6 address and taking name resolution out of the picture.  Anyway, I note that Exchange 2010 will not install without IP6...

Anyway, thanks again!!

-Dave

[Eclarsys Support]

Thank you for the explanation, this will help us reproduce the problem here.

We haven't tested PopGrabber in IPv6 networks, we will check this out and upgrade our code to avoid this problem in the future. The Net Framework definitely works with IPv6, so it could be something our mail module is doing wrong.

[zxdavb]

Just to let you know that the Exchange server, and AD, and the PopGrabber where all on the one PC.

Actually, it's a VM (on VMware) - I could be talked into making a copy available to you (think that it wouldn't break licensing rules because I'm using a eval/demo version anywany until it is released to MAPS customers), I'd just have to work out a way of removing the personal data.

Let me know via PM/email...

[Eclarsys Support]

Thanks!

We are in the process of installing a test server in an IPv6 network to verify that PopGrabber always uses IPv4 addresses, because many SMTP Server still do not support IPv6 networks (or are disabled by default).

We will let you know the results in a few days.

Regards,

Eclarsys Support

[Eclarsys Support]

We haven't been able to reproduce the problem in our test server. There must be something different in the server configuration since our DNS resolves IPv4 addresses unless we specify the -6 switch.

However, we have generated an updated mail library that forces IPv4 connections for the POP3 and SMTP servers (before it was set to automatically detect the protocol type).

Please replace the "MailLibrary.dll" file by extracting the attached file in the installation directory (usually C:\Program Files\Eclarsys\PopGrabber Free).

Let us know if this works for you.

Regards,

Eclarsys Support