muttrc vs postfix main.cf

[Don W. Jenkins]

To all those who answered with various suggestions for my muttrc file, I 
have applied all suggestions, with no luck in getting my "From:" header 
completely under control in my sent e-mails.  The Kplug listers did 
correctly identify the problem as being not in mutt, but postfix, as I 
was able to get the last half of the e-mail address corrected by 
changing "mydomain" and "myorigin" in postfix.  Now the "From:" header 
reads:
 
"Don W. Jenkins<oakman at sc-zg.com>"

"oakman" is my username on my computer system, and I need that part to 
be "dwjenkins", but I don't see where postfix reads that.  I see plenty 
of places where mutt would read it, if it were allowed to.  Right now 
postconf -n yields:

alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
append_dot_mydomain = no
biff = no
config_directory = /etc/postfix
mailbox_command =
mailbox_size_limit = 0
mydestination = localhost.localdomain, localhost.localdomain, localhost, 
sc-zg.com
mydomain = sc-zg.com
myhostname = dwjenkins.sc-zg.com
mynetworks = 127.0.0.0/8
myorigin = sc-zg.com
recipient_delimiter = +
relayhost = smtp.west.cox.net
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)

The main.cf in Ubuntu is much more abbreviated than I am used to, or at 
least a lot of commentary is omitted, and all the variables are lumped 
together in one place with very little else in the file.  It is a very 
short file, so I don't know if there are some missing possibilities, one 
of which would solve things. 

Thanks for any thoughts,
Don J.