If you are experiencing some POP access problems with communication programs such as Outlook, Outlook Express and Thunderbird, you need to download a tool called Gmail POP Troubleshooter directly from the Google Web site.
This tool will immediately repair your POP access to its server. Actually it will not take too long, downloading this program. What does this tool do? When you run this tiny program, its role is to check and verify your client settings, server ports, and your connection to Gmail. This program will be able to pinpoint any errors and provide you with instructions on fixing these errors. Gmail POP Troubleshooter will also generate a detailed report with your settings and test results. If you still have troubles, you will have the option of sending the report to the Google Group for further help assistance.
Please verify if you are meeting the following requirements:
Outlook 2000, 2002, 2003, and 2007, Outlook Express 6, and Thunderbird 1.5. Currently only available for Windows.