need help about activation email message

hi everyone i need help about this:
some members join my forum but they said they didn't had ana activation email and they can't login or register again cuz thei name/email is already used how can i fix it?

I wonder if your members are using a Hotmail address - I've discovered an issue with Hotmail as they don't usually forward activation emails.
As admin, you can complete their activation by going into admin>users & groups>users>inactive users - this lists users who've registered but not completed the activation process. Click the members you want to have access and 'Activate' their account.