I need to setup mail server for sending from PHP scripts only. I'm not needed to receive email or sending it by another way. Preferable is the Postfix (it is easy than Sendmail, for example). Ssmtp is doesn't suit me.
Is there some manual or ready-to-run config for this?
freebsd handbook is the best resource about your requirements:
http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/mail-using.html
https://wiki.freebsd.org/SecureSSMTP
i prefer ssmtp