If an user requests at [[Special:Userlogin]] a new password, the system responds
always with [[MediaWiki:Passwordsent]] ("A new password has been sent to the
e-mail address registered for "$1". Please log in again after you receive it.")
as well a no password is stored in user preferences.
This is very illogical and user complains then via email (ask the OTRS support
teams) that no new password comes.
And believe me... most users don't know if they have entered an email adress at
time of account creating or later.
Solution: Create a new message like "Sorry, for this account no email is stored,
we cannot send you a new password" and check at time of requesting a new password.