SBS 2003 Exchange Pop3 Connector Errors

Posted on 2008-10-10
Last Modified: 2013-11-29
For several months now I have been receiving these error messages via the SBS server performance reports.

Critical Errors in Application Log

Source                          Event ID      Last Occurrence      Total Occurrences
POP3 Connector               1019      10/9/2008 4:19 PM      9 *
The message download process finished with one or more errors.

Source                           Event ID      Last Occurrence      Total Occurrences
POP3 Connector                1023      10/9/2008 4:19 PM      9 *
The downloading process for mailbox <pop**** []> was ended with one or more errors.

Source                           Event ID      Last Occurrence      Total Occurrences
POP3 Connector                1036      10/9/2008 4:19 PM      9 *
An error occurred during a POP3 transaction to server < [pop****]>. The error is 0 (The operation completed successfully. ).

Source                           Event ID      Last Occurrence      Total Occurrences
POP3 Connector                1071      10/9/2008 2:11 PM      1
An error occurred when Exchange Server attempted to deliver a message. The message is in the SMTP queue.

Source                           Event ID      Last Occurrence      Total Occurrences
POP3 Connector                1029      10/9/2008 10:41 AM      2 *
Access was denied to the mailbox <> logging on as <pop****>. Verify the password for the mailbox account, and try again.

I have tried to establish solutions via the internet and by contacting our mailbox provider but to no avail. I have searched EE's knowledgebase and whilst there are similar occurences none seem to provide a working solution to this problem.

I have to say these errors do not seem to be having a direct effect on our system but are more an annoyance. Its interesting to note that at weekends when the office is empty but the connector still connects on the same schedule (every 15 minutes) there are no errors in the following days reports This leads me to believe it could be client related.

We have 15 clients connected to our SBS box which is running 2003 R2 with all updates installed. We are not currently running ISA server but plan to do so. Additionally OWA & VPN are installed as well.

Email out is via DNS (i.e. not via our mailhost) and we retrieve our mail from a catch all address box which Exchange then routes to the correct user when downloaded via the connector.

I know this is not a major problem but it is annoying that I have not been able to resolve it so would appreciate any assistance.

Many thanks in advance


Question by:jezhunt
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Expert Comment

ID: 22685278
Presumably you are using the native POP3 collector in SBS? This sounds like a problem with the remote host or a connectivity issue. Can you try a 3rd party collector and see if you get the same results? Additionally is there any reason why you are not having the email delivered to exchange via SMTP as that was what exchange was designed for. Furthermore ISA will not add anymore resilience to your SBS server unless the server has 2 NIC`s one of which is public facing. This is NOT though a good security practice at all and far better to have the server NAT`ed behind a firewall. In this instance with only 1 NIC ISA can only act as a proxy.

Author Comment

ID: 22685394
Hi scurlaruntings,

Thanks for getting back to me. Yes we are using the native POP3 connector which worked with no problems initially. I set the system up April last year and it run for 12 months with no probs. I did download a third party collector the other day but haven't had time to configure it yet. My view on this though is I would prefer to keep everything 'in house' to minimise conflicts and the potential of any future problems being caused by several different software vendors.

There is no particular reason for using POP3. I understand that SMTP will increase server workload & could lead to loss of email should the server go down. I would need a bit of guidance to set it up as when I questioned my mailhost about ths they said I couldn't do it with the type of account I had which they refer to as pop3 'mailmapper'

I note your comments about ISA. We do have the second NIC which is currently disabled. Our system is behind a Netgear modem / router utilising its firewall. I was led to beleive ISA was the de facto security standard for SBS but you seem to disagree with this. I know it looks difficult to setup and probably would just lead to endless amounts of hassle for little payback.

Thanks for your comments so far



Expert Comment

ID: 22685444
Firstly the native POP collector with SBS is not very good. In that its not flexible enough to allow further functions as will a 3rd party collector. The 15 minute schedule is an example of this. If you was using a 3rd party collector this could be down to at least a 1 minute. If you was using SMTP though your email would be real time. Furthermore POP3 based email allows for no email filtering in regards to SPAM. Using a catch all account compounds this further and adds another layer of complexity that simply doesnt need to be there. As for increasing the server workload the answer is no. Exchange was designed for use with SMTP. Not POP delivery. All traditional MTA`s use SMTP for delivery. When you use a collector you have no control over your email.

As for loosing mail there are better solutions than what you have implemented. You can have additional MX record with a lower or higher cost and have the mail server configured for fail over in the event that the 1st MX is not available or round robin and have the MX`s load balanced. Naturally both require another mail server.

ISA although a good product is NOT recommended as a perimeter firewall purely because it sits on a MS OS. On SBS this would be compounded further because it sits on your domain controller. You NEVER put your DC in the network perimeter. In order to use ISA`s full functionality you would need to deploy the client to all PC`s as well as make your DC public facing. Thats a disastrous approach and more complexity than what its worth. Hence why SBS2008 doesn't have ISA installed and only supports 1 nic.
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Author Comment

ID: 22685515
Ok, so you've prety much convinced me of what I knew in my mind, SMTP is the way forward and ISA is going to potentially cause more problems than its worth.

So how do I go about setting our box up to use SMTPi n the most effective way?




Expert Comment

ID: 22685533
You need to contact whomever owns your namespace IE your domain registrar and ask them to create an MX record that points to your mail servers External IP address. Open port 25 on your firewall to point to your exchange box. In addition always ask the registrar to create a PTR record (reverse record in DNS aswell) in order to ensure correct mail routing. You will then need to purchase a 3rd party antispam utility, or use the native functions of IMF recipient filtering etc that are built into exchange 2003 SP2.

Author Comment

ID: 22685564
Sounds simple enough, lets see what happens

Author Comment

ID: 22690219
Well this is what I've done and it seems to be working, although I have a few questions which may seem a little lame but I am just trying to ensure what I have done is right.

First I logged into to my domain registrar's control panel and created an A record,, pointing to our SBS's box external facing ip address. Then I added an MX record, pointing to and gave it a preference (priority) of 10. There were two MX records there already, both with preference of 50 (lower priority) pointing to the domain registrars servers and I have left these for now.

Then I logged onto our router and opened port 25. In Exchange system manager I added to address space in the SMTP connector properties and also changed the 'use DNS to route each address' option to 'forward all email through this connector' being our registrars relay server, my theory being everything would then be coming in and going out via their servers. I Let the whole thing stew for an hour or so, then stopped the pop3 connector service and sent an email to my business address from an external hotmail account. Hey presto it arrived almost instantly at our SBS box. So at the moment it seems a success.

My questions are

I didn't have an option in the domain registrars control panel to create a PTR record, is this otherwise known as a Cname?

Where is all the undeliverable mail going now i.e where the prefix to is not recognised as an exchange account? Using pop3 this was all sent to me as the system admin and I could forward to the relevant user if it was caused by a mispelt address.

How do I direct several addresses to one person? For example our office manager has her own address but also deals with enquiries made through our corporate address

Any other relevant advice based on what I've described is much appreciated and thank you for your assistance so far.



Accepted Solution

scurlaruntings earned 250 total points
ID: 22691242
The PTR record can only be created by your ISP as they "own" your subnet. A CNAME is a canonical name/alias and has no relavence in this context.

There are a number of ways to route email. Either create a distribution list for those said mailing address`s in AD or add alias`s for those account to the said user object in AD.

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