If a user forgot his password, he can reset his password himself. The feature “forgot password” is shown on the login page.
Resetting the password is only possible with a specific password-reset link.
You should update the email-templates that are shipped with Portrait. See Customize Mail-Templates
To use this feature, you need to setup up the Mailer. See https://portrait.atlassian.net/wiki/spaces/PA/pages/93028539/General+settings#Mailer