The System.Web.UI.WebControls.ChangePassword control will send an e-mail message confirming that the password has been changed when the ChangePassword.MailDefinition property defines an e-mail message to send.
The e-mail message contains automatic replacement fields for the user name and password. You can use the ChangePassword.SendingMail event to modify the e-mail message before it is sent to the user.
Sending user account names or passwords in e-mail is a potential security threat. E-mail messages are typically sent in plain text and can be read by special network "sniffing" applications. To improve security, use the mitigations that are described in Securing Login Controls.
For more information about handling events, see Handling and Raising Events.