To change your email password you must login to your SNC Email account at http://mail.sentco.net.
Once you've logged in, click on "Settings" in the upper right-hand corner. This will open the settings window. In the bottom left corner of the settings window is a "Password" link. Click on it and another window will open. Complete the form by entering the appropriate information and then click Save.
Please note that setting up an alternate email is optional. This feature is handy if you ever forget your password. In that case, if it is setup correctly, you can click on the forgotten password link on the email login page and the system will send you an email with your password to the alternate email address.