if I try the 'forgot password' link no mail is send, although Indexu says 'mail send...'
(haven't tried other sendmail functions yet)

I had similar problems with another script (newsletter), which said:
Warning: mail(): SAFE MODE Restriction in effect. The fifth parameter is disabled in SAFE MODE. .....

So I guess it might be the same problem with Indexu.

Is there any way around that problem...?
Or an advice to my ISP on how to change/correct PHP settings?