Mutt problem

[James McDonald]

when sending mail from mutt it seems to be sending my non-internet 
kosher address as the mail from: and there fore getting rejected.

<linux-users at linux-sxs.org>: host mail.linux-sxs.org[64.116.183.6] said: 550
    5.7.1 <jamesm at amd.jmcd.local>... Please see
    
http://spf.pobox.com/why.html?sender=jamesm@amd.jmcd.local&ip=220.233.22.154&receiver=mail.linux-sxs.org:
    domain of sender jamesm at amd.jmcd.local does not exist (in reply to MAIL
    FROM command)


what does one edit in muttrc to make sure the mail from is correct ?