Question : configure Mutt to use remote SMTP/POP mail server.

the requirement is to send e-mails automatically with attachments from Linux to Windows mail server.  there is no mailserver like postfix/sendmail/qmail on Linux host.

i preferred mutt to send e-mail attachments automatically in shell script.
how to configure mutt to send/receive e-mails to the remote windows mail server using POP3/SMTP.

Answer : configure Mutt to use remote SMTP/POP mail server.

If you want your local postfix server to forward all the mail to a specific SMTP server for onward delivery then this can be easily achieved.
See http://www.postfix.org/BASIC_CONFIGURATION_README.html#relayhost