Today's colleagues feedback, the e-mail sent to the customer's e-mail can not receive the mail, the customer can send us an e-mail can be received, relatively wondering, it was possible before, and the server did not make any changes to the settings. 1, the first step is to think of the server DNS resolution, check the server's DNS is 127.0.0.1, modified to the DNS provided by the access provider, the server can not directly access the Internet 2, after modifying the DNS, still invalid, Also invalid after restart. After using ipconfig, the information of windows ipconfig configuration can not be obtained, and even the manually set IP is invalid. 3, find three methods on the Internet, one is to change the TCP /IP installation protocol, reload after uninstallation, two, disable the network card in the task manager, enable in the network connection properties, three, repair winsock4, three methods are Tried, not good 5, finally, uninstall the NIC driver, re-installed 6, found it is not good 7, restart the server OK (windwos is amazing) Repair Winsock method: the computer can not be online, prompts "ldquo; query The TCP IP setting of this connection failed and could not be processed. Reinstalling the NIC driver and reinstalling TCP/IP could not be solved. Sometimes the WINSOCK can be repaired online. Then the way to repair WinSock is very simple: click Start → run, enter CMD, open the command line, then enter netsh carriage return; then enter winsock Enter; enter reset to enter the car; after the repair is completed, the prompt needs to be restarted, then restart the computer Just fine. Reinstall TCP/IP method: TCP/IP protocol installation method: www.dnzg.cn1, start → run → regedit, open the registry editor, delete the subkeys under the following two keys: HKEY_LOCAL_MACHINE\\System\\CurrentControlSet\\ Services\\WinsockHKEY_LOCAL_MACHINE\\System\\CurrentControlSet\\Services\\Winsock22, open the c:\\windows\\inf\ ettcpip.inf file with Notepad (if the system is installed under the C drive), find: [MS_TCPIP.PrimaryInstall]; TCPIP has properties to displayCharacteristics = 0xA0 ; Save 0XA0 to 0x80 and close. 3. Open the TCP/IP properties of the local connection, click Add Protocol → Install from Disk → browse to the nettcpip.inf(c:\\windows\\inf\ ettcpip.inf) file you just modified, and then select “TCP/IP Protocol & rdquo; (do not choose that TCP /IP version 6), OK. After this step, it returns to the window of the network connection, but at this time, the "Uninstall" button is already available. Select the TCP/IP protocol, then click the “Uninstall” button to delete the TCP/IP protocol and restart the computer. 4. After rebooting, follow the third step and re-install the TCP/IP protocol. 5, restart the computer again, the problem is solved. (You can set the IP address as needed)