North Rock Communications is warning its customers about a series of e-mail messages being mass-mailed to them asking for their user credentials in return for a bandwidth upgrade.The company sent an e-mail to its customers yesterday warning that this is a widely used form of identity theft and that customers should assume any requests they receive asking for such confidential information are malicious and should be deleted from their inboxes.“Please be aware that North Rock will never e-mail or contact you asking for your username, password or any other confidential information,” the e-mail from the company stated.Customers who have received such an e-mail and have since continued to use their user credentials or other data on the North Rock website are asked to contact the North Rock Helpdesk at 540-2700 to have their password reset.