sendmail trusted-users not picked up

I've searched many forums and tried a lot but I can't get it working. I want to be able to set the FROM address but it's changed to the main domain name when received.

So I try to send from oscar(at)domain2.com but it changes to oscar(at)domain1.com.

In the mail header I get:
x-authentication-warning: domain1.com: www-data set sender to
oscar(at)domain2.com using -f

I tried putting 'www-data' in /etc/mail/trusted-users
And put 'FEATURE(`use_ct_file')' in the /etc/mail/submit.mc.

Restarted sendmail but no effect.