From Online Manual
If a forum is configured to require email activation before login, an email will be sent to the email address provided at registration. The username and activation link are displayed in this e-mail. Selecting the activation link activates the member's account and prompts them to login. If a problem occurs with the activation link, the email also provides an activation code that can be used to complete the process. Note that a link to reset the password may be included in this e-mail, depending on the activation method enabled on the forum.