POP3 Access to Exchange Server 2003
I just spent some time troubleshooting POP3 access to my Exchange Server.
I wanted to connect to Exchange with Mozilla Thunderbird in order to allow me to connect from home with my Mac, so I configured the POP3 server under the Exchange Manager and configured my Thunderbird client with my account details.
Unfortunately, I got no mail downloaded to the client. Thunderbird reported that it was connected to the mail server in the bar at the bottom of the Thunderbird client – but nothing was being logged in the Thunderbird – Error Console. No errors – no clues as to what was going wrong.
Another thing I noticed at this point was that if I tried to telnet to port 110 to see what was going on I wasn’t seeing a banner and the connection would just drop as soon as any data was sent from my end.
I tried to resolve this by removing the security requirements for the connection, so in Exchange Manager I unchecked Require Secure Channel and I changed the Authentication to Basic. I had to obviously make the relevant changes to the client setup too at this point.
After restarting the POP3 service I was able to successfully retrieve mail so I then began a process of enabling the security features until I found what the cause of the problem was.
As soon as I tried to use SSL I was back in the situation of not getting mail but not receiving an error message.
After a while I decided to change the certificate under Exchange Manager for the POP3 Server. The one I had previously chosen was evidently not intended for the purpose of such authentication.
I chose a different one whose intended purpose was ‘Server Authentication, Client Authentication’, and that resolved all issues. Upon the next client access attempt Thunderbird was obviously presented with the certificate and popped up a dialog to request if it was to trust the certificate (this never happened before with the first certificate I had chosen). It was now possible to enable all security features for the connection.
In my setup I’m using self-signed certificates. I did quite a bit of Googling in coming up with this solution and never found any reference to the certificate chosen being the problem so that was my main motivation for writing this up – hope it helps somebody save some time, I never figured out whether it was a Thunderbird issue or an Exchange Server issue, but I suspect it was Exchange.
For info – I was using Thunderbird 2.0.0.14 and Exchange Server 2003 SP2.