virtual mail postfix help

[wsonar]

I can send fine now from clients to internal and external and I can send from php scrip to internal but when I try php script to external

it's sending from:www-data instead of who I specify

[wsonar]

my server puts from=<www-data@computername.mydomain.com> //which is not where my mail pointers point
it's in the /var/log/mail.log

when I send it to myself the virtual domains I'm hosting on this box I get it no problem and the header information looks right

I assume it's getting rejected from gmail and yahoo because of this

recipient invalid domain (in reply to RCPT TO command))

when I send from thunderbird the mail.log show's sent from correct virtual server
but when I send from php it puts from=<www-data@computername.mydomain.com>

[wsonar]

a php issue from here