We use pop accounts as a backup when our server or internet connection is down. We've recently upgraded to sbs 2008. 

I've added our backup pop accounts via the SBS console pop conenctor. When i hit retreive now it give me an error. 

in the event log the error is described as:

```
The TCP/IP connection with the '[pop sever]' server was terminated while 
trying to   access the '[email@email.com]' mailbox. The cause may be 
server problems, network problems, a long period of inactivity, a
connection time limit, or incorrect connection settings.

```

This only happens if there is a message in the account. if the account is empty it gives no error and says completed successfully. 
The message can be any size and it still throws this error. It times out in under a minute.

Looking at the pop verbose logs it gets as far as the downloading message stage before it times out. ie it authenticates, checks how many messages there are and begins the download. 

I know it's not a firewall issue because i the relevant ports are open on the hardware filewall and the server. 

I can download the mail from these pop accounts when i set one up in outlook directly. 

I also don't think it's a virus scanning problem as I have this problem even if i disable Symantec Endpoint Protection 11 on the server- which is what we use.

any ideas anyone?
['https://serverfault.com/questions/12739', 'https://serverfault.com', 'https://serverfault.com/users/3955/']
Download the network monitor from <http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=983b941d-06cb-4658-b7f6-3088333d062f> and use it to watch the connection to the POP3 server.

POP3 is a simple protocol and POP3 commands are plain text. In the output from the network monitor you'll be able to see the commands sent by your server and the responses from the POP3 server. It should be easy to see exactly what the problem is.

The latest version of the network monitor is a bugger to use, but the help is reasonably good and has examples.

JR

----8<----
Response to Charlie's comment:

I doubt the segment lost is significant. TCP is a fault tolerant protocol and even if packets were lost TCP will correct the loss.

If the trace actually shows the mail then the POP3 connector is getting as far as downloading the message. The packet before the mail should be a packet from your server to the POP3 server with the RETR command in it. The POP3 server responds to RETR by sending the mail. After the packet with the mail in, your server should send a DELE command, then finally a QUIT.

If there are no packets after the mail is sent to your server, that suggests your server is failing to spot the end of the message so it's hung waiting. This rings a faint bell with SBS 2003. I have only a faint recollection of this, but I'm fairly sure I've seen something similar in 2003 and that was due to the anti-virus. Someone had installed an AV that processed mail downloads and that was interfering with the connector.

Have you considered uninstalling the AV from the server to see if that helps? We've only done a couple of SBS 2008 installs, and only one of those uses the POP3 connector, but it does work. As a last resort I have actually written a POP3 downloader that I'd be happy to pop on Sourceforge.
I would recommend (if you havent already) trying a differnt pop3 account on seperate host if possible to rule out any problems either with the host or some kind of incompatibility between the two.