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POP3 server name cannot be found

Some of our users got error message when they press F5 or "send/Receive" buttom in the Outlook2000. The error message is:

"The POP3 server name you specified cannot be found. Please check the name and try again"

The POP3 server name is correct and the Internet connection is fine.
The user need to restart the Outlook2000, or sometime need to restart the Windows to solve the problem.

This problem only occuried in Outlook2000 which access the mail server by POP3 service.

On the server side(running Exchange server 5.5),

There's 2 error messages in event viewer application log which seems to be related to the problem

"Microsoft Exchange POP3 Server encountered error 0x40 sending response to the client."
"POP3 connection to XXX.XXX.XXX.XXX lost."

Any idea please?

1 Solution
1. From a client that experiences the problem, try using Outlook Express to see if you can POP mail.

2. From the same client, try telneting to the Exchange server using the POP port.

TELNET (mail server name or IP) 110

You should get the MS POP3 prompt if successful.

3. If a firewall exists between the users and the mail server, make sure that POP3 is allowed in and out (to and from the mail server).

4. Check that the DNS entries the client uses for the mail server are correct.

5. Try uninstalling and reinstalling the Internet Mail service in Outlook.

percy_kAuthor Commented:
Thx bz7,

1. Client no problem in POP mail with Outexpress

2. I can telnet the port 110 from the problem machine.

3. The firewall is allow POP3. Actualy, the problem may solve if the user restart the machine.

4. DNS fine, the problem still there even I bind the IP in host table or enter IP address in the POP3 field directly.

5. I reinstalled same user's machine but still ahve this problem.

This problem occur not only one, but six users.

BTW, anyone know what mean the error message?
"Microsoft Exchange POP3 Server encountered error 0x40 sending response to the client."
"POP3 connection to XXX.XXX.XXX.XXX lost."

They come up together in the Exchange server event log everytime when client's have the problem.


What service pack are you running on the Exchange server? They are up to 3 I believe.
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Exchange 5.5 is actually on SP 4. ;-)

I am not familiar with the error you get. Its as if the Exchange server was having trouble maintaining a network connection with these clients when using Outlook 2000.

Could the issue be related to a hardware configuration on the clients?. Perhaps the NIC or modem?

If any of the clients are W2K, do they have any events in their event logs?

percy_kAuthor Commented:
Using Exchange Server 5.5 with SP4

And both W2k and Win98 client has this problem in using Outlook

I am not sure if it is probably the Outlook 2000's problem because our Mac users is fine even they connection with POP3 too.

Its a long shot, but what SR are you using for MS Office? The latest is SR 2, available here:


Do the W2K clients have any events in the event log?

Hello percy_k

this question is open for more then 2 months
time to clean up
if not stated otherwise

my recom will be
-PAQ and no refund
-this will be finalized by an EE Moderator
-with no further update (21.09.2002)


posted by ToolzEE v1.0
Question has been closed as per recommendation

JGould-EE Moderator
Question has a verified solution.

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