dynamic DNS + mailserver

[pat bey]

First I like to know if a mailserver such as postfix
can run using dynamic DNS.  I using dyndns.org for
Dynamic DNS and trying to run postfix with a hostname
of hijra.homeunix.com.  Sense installing postfix
system mail that normally goes to root is now not even
generated by system is this a sendmail only thing or
does postfix generate system mail to root as well. 

After fixing alot of the problems that I had still got
this one which is driving me insane.  Whenever I send
a mesg to tweaxor at hijra.homeunix.com 
maillog shows the mesg as being queue and sent to
maildir.
#mail 
0 messages for tweaxor
# pine
0 messages in INBOX

Do I have to modify any files that where used by
sendmail to get it find the mail. In
/usr/local/etc/postfix/main.cf 
myhostname=hijra.homeunix.com
myorgin=$mydomain
mydomain=hijra.homeunix.com

#postfix check
shows nothing
Thanks for your time and consideration

=====
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-------------- next part --------------
Jul 18 03:02:30 hijra postfix/qmgr[182]: 5200BE25: from=<root at hijra.homeunix.com>, size=2373, nrcpt=1 (queue active)
Jul 18 03:02:30 hijra postfix/local[1119]: 5200BE25: to=<root at hijra.homeunix.com>, orig_to=<root>, relay=local, delay=0, status=sent (maildir)
Jul 18 08:33:51 hijra postfix/postfix-script: starting the Postfix mail system
Jul 18 08:33:51 hijra postfix/master[184]: daemon started -- version 2.0.6
Jul 18 18:18:58 hijra postfix/smtpd[1167]: connect from web41205.mail.yahoo.com[66.218.93.38]
Jul 18 18:18:59 hijra postfix/smtpd[1167]: 07F9DDAD: client=web41205.mail.yahoo.com[66.218.93.38]
Jul 18 18:18:59 hijra postfix/cleanup[1168]: 07F9DDAD: message-id=<20030719001553.15729.qmail at web41205.mail.yahoo.com>
Jul 18 18:18:59 hijra postfix/qmgr[186]: 07F9DDAD: from=<phaza7 at yahoo.com>, size=809, nrcpt=1 (queue active)
Jul 18 18:18:59 hijra postfix/smtpd[1167]: disconnect from web41205.mail.yahoo.com[66.218.93.38]
Jul 18 18:18:59 hijra postfix/local[1170]: 07F9DDAD: to=<tweaxor at hijra.homeunix.com>, relay=local, delay=0, status=sent (maildir)