Logging In from a local app
If your organization restricts which IP addresses you can use, and you log in from an untrusted address, your login is blocked until you activate the IP address. Salesforce.com automatically sends you an activation email that you can use to log in. The email contains a security key that you must add to the end of your password. For example, if your password is mypassword, and your security token is XXXXXXXXXX, you must enter mypasswordXXXXXXXXXX to log in. For more information, see “Resetting Your Security Token” in the Salesforce.com online help.
Example from PowerCenter: