Two errors appear when using Microsoft Outlook, with error codes 0×800CCCOF and 0×8004210A. Is there a way to prevent these errors from appearing? Another issue is my internet download speed. Despite being on a 24000kb connection SpeedTest reports that the speed is only 3600kb. My ISP has claimed the problem is not at their end. How can I get full speed on my internet connection? The computer is running Windows XP.

Since you have not reported that the email service has been interrupted I am assuming that your email still works correctly, but these error messages appear when using Outlook. The 0×800CCCOF error code indicates that the connection with the mail server was interrupted, and 0×8004210A is the code for a mail server time-out. Both of these error codes indicate that Outlook is having difficulty talking with the mail server, or the mail server is timing-out (i.e. not responding to requests from your email client in a timely fashion).

A potential cause of this issue is third-party security software running on the computer, such as firewall software. To check whether the security software is causing the problem, as a first step you could try disabling the firewall software to check whether the problem persists. However, be very careful when completing this procedure, as during this time the computer will be vulnerable to attack. Therefore, I suggest before disabling the third-party firewall you disconnect the computer from any networks (including the internet), then disable the firewall software, and then enable the Windows XP firewall. This can be done through the “Start” menu > “Control Panel” and opening the “Windows Firewall” control panel (you may need to first click the “Security Center” category). In the Windows Firewall window click the “General” tab and ensure that the firewall is set to “On”. Click OK to close and save. This will provide the computer with basic protection while you determine whether the third-party security software is causing the problem. You can now reconnect the computer to the internet, to check whether the error persists. If not, it seems a configuration with the firewall is causing the problem. Without further information about the firewall which you are using, I can’t provide any more information in this regard. If you could please contact me again with this additional information then I can investigate the problem further.

However, should the problem continue even with the third-party firewall disabled, it seems that the problem is not related to this security software. In this case, first you need to re-enable the third-party firewall. You should not need worry about disabling the Windows Firewall, as the third-party firewall should automatically do this when it is enabled, to prevent conflicts between the Windows firewall and the third-party firewall. Another possible cause of the problem is the antivirus scanning features of your third-party security software. This software may be scanning all outbound email messages and this creates a bottleneck in the entire process, making Outlook think that the mail server has timed-out and is not responding. To determine whether this is the cause, disable inbound and outbound email scanning in your antivirus client. While viruses will no longer be detected when downloading email, this should not present a major security risk to the computer as your antivirus real-time scanner should still be functioning. Therefore, should any email borne virus infected files attempt to run, they will be detected by the real-time scanner upon their execution. Once the email scanning feature has been disabled, check whether the problem continues. If the problem stops, you can either leave the antivirus email scanners disabled, or I suggest you check whether any updates are available for the antivirus software which may resolve this issue.

Where the problem continues even with the email scanning disabled, you will first need to re-enable the email antivirus scanner. Once this is done, our attention can turn to the next most likely cause of the problem which is potentially the timeout on the server being too short, causing Outlook to think that the connection has been interrupted. So, you can try increasing the server timeout. In Outlook, go to the “Tools” menu > “Email Accounts”. Select ?View or change existing e-mail accounts? and click “Next”. Select your email account in the list and click “Change”. In the next window, click the “More Settings” button and then the “Advanced” tab. Increase the server time-out setting to check whether this resolves the problem.