How to set sending e-mail address?

I'm trying to figure out how to set the sending address when sending e-mail from PHP, but it doesn't seem like I'm having much success.. When I look in the mail queue, I always see 'wwwrun@web.domain.tld' as the origin (the web server user). In my sending routine I set headers like this: $hdrs = array(

'From'    => $MAILFROM,

'Subject' => iconv(strtoupper(CHARSET), "ISO-8859-1", $subject), 'Reply-To' => $MAILFROM, 'Date' => date("r"), 'Return-Path' => 'POSTMASTER@domain.tld' ); Oh, the mail sent doesn't use the Return-Path I set, it's still set as wwwrun@web.domain.tld. What else can I do, and what have I missed? Anders