mail() function
 

Can somebody tell me in which file is the mail() function for sending mail from forum bacause I need to change a charset??

Emailing to all members?

That would be email.php in the admin directory. Try that.

Not for that! I need it for sending the mail vhe registrating or when somebody replys and other

Well I'd say they'd all be in seperate files.

register.php for register emails.
newreply/thread.php for reply/thread emails.

Ask at vBulletin.org. we dont suport hacking of .php files here :)