If you receive an error message when performing a Send and Receive in Outlook or Outlook Express, examine the message for the error code. The following error codes are the most common:
All of these error codes are typically associated with Outlook or Outlook Express not being able to communicate with the mail server. This can happen if you are not connected to the Internet, a firewall is configured wrong, or the account settings are wrong, among many other reasons. To troubleshoot the problem, try the following steps:
- Verify you are connected to the Internet. Open up your web browser and visit a web page (such as this one). If the web page loads, then you are connected to the Internet.
- Verify your e-mail account settings. To do this, you will need to contact your email provider (or visit their online support site) and find out how your email program should be setup. Most ISP use POP3/SMTP for e-mail access, in which case you will need to verify the POP3 server name, the SMTP server name, your username, and your password. If you need help imputing this information into outlook, check out the instructions here: //support.microsoft.com/kb/287532/ 
- Temporarily disable your antivirus program and any firewalls. If you can then send and receive mail successfully, your antivirus/firewall program is configured incorrectly.
- If you have performed the previous three steps, but you still receive an error message, it is possible the email server is down. Wait 30 minutes and try again. You may also which to restart your computer at this point as an additional troubleshooting step.
- If you still cannot send or receive your mail, you may need to reinstall your email program. For details on this, check out this Microsoft article: //support.microsoft.com/kb/813514