Help: postfix confusion

["counterattack_@eml.cc" <counterattack_@eml.cc>]

Hello, please reply directly to me since I'm not on
the list and won't be until I can use my ordinary
email address.

I use a dialup machine, and KMail as my mail client.
When sending mail, I use the `sendmail' command
provided by postfix.  But like sendmail it tries to
send mail directly using mylogin@debian, where debian
is my hostname.  I can't get it to force a send as
"jamesbuch@iprimus.com.au" like I could do with sendmail
using sendmail -f jamesbuch@iprimus.com.au.

How can I get postfix to set "from" correctly?

Many thanks!
James
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  counterattack_@eml.cc
  counterattack_@eml.cc

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