Hi Till, thanks for your reply!
I investigate today and that's occours just if I sent mail using /usr/sbin/sendmail as root, with external clients works fine
Apr 26 20:37:17 web postfix/smtpd[5929]: connect from mail-gx0-f175.google.com[209.85.217.175]
Apr 26 20:37:17 web postfix/smtpd[5929]: NOQUEUE: reject: RCPT from mail-gx0-f175.google.com[209.85.217.175]: 550 5.1.1 <JUST_TEST@mixdinternet.com.br>: Recipient address rejected: User unknown in virtual mailbox table; from=<filipealvarez@gmail.com> to=<JUST_TEST@mixdinternet.com.br> proto=ESMTP helo=<mail-gx0-f175.google.com>
Apr 26 20:37:18 web postfix/smtpd[5929]: disconnect from mail-gx0-f175.google.com[209.85.217.175]
But i've got another serious problem with ISPConfig 3.0.1.1 and Ubuntu 8.04

All ISPConfig functions with system calls (ln, mv, cp etc with exec() php function) like add WebSite/Shelluser "crash's" and many server.sh/server.php process has been created a lot:
# ps aux|grep "server.[sh|php]"
root 6421 0.0 0.0 2500 1012 ? Ss 23:53 0:00 /bin/sh -c /usr/local/ispconfig/server/server.sh > /dev/null 2>> /var/log/ispconfig/cron.log
root 6423 0.0 0.0 2508 1088 ? S 23:53 0:00 /bin/bash /usr/local/ispconfig/server/server.sh
root 6424 0.0 0.2 25244 7888 ? S 23:53 0:00 /usr/bin/php -q /usr/local/ispconfig/server/server.php
root 6437 0.0 0.0 2500 1012 ? Ss 23:54 0:00 /bin/sh -c /usr/local/ispconfig/server/server.sh > /dev/null 2>> /var/log/ispconfig/cron.log
root 6439 0.0 0.0 2508 1088 ? S 23:54 0:00 /bin/bash /usr/local/ispconfig/server/server.sh
root 6441 0.0 0.2 25244 7896 ? S 23:54 0:00 /usr/bin/php -q /usr/local/ispconfig/server/server.php
root 6455 0.0 0.0 2500 1012 ? Ss 23:55 0:00 /bin/sh -c /usr/local/ispconfig/server/server.sh > /dev/null 2>> /var/log/ispconfig/cron.log
root 6460 0.0 0.0 2508 1084 ? S 23:55 0:00 /bin/bash /usr/local/ispconfig/server/server.sh
root 6461 0.0 0.2 25244 7892 ? S 23:55 0:00 /usr/bin/php -q /usr/local/ispconfig/server/server.php
root 6491 0.0 0.0 2500 1020 ? Ss 23:56 0:00 /bin/sh -c /usr/local/ispconfig/server/server.sh > /dev/null 2>> /var/log/ispconfig/cron.log
root 6493 0.0 0.0 2508 1088 ? S 23:56 0:00 /bin/bash /usr/local/ispconfig/server/server.sh
root 6495 0.0 0.2 25244 7892 ? S 23:56 0:00 /usr/bin/php -q /usr/local/ispconfig/server/server.php
root 6569 0.0 0.0 2500 1016 ? Ss 23:57 0:00 /bin/sh -c /usr/local/ispconfig/server/server.sh > /dev/null 2>> /var/log/ispconfig/cron.log
root 6572 0.0 0.0 2508 1088 ? S 23:57 0:00 /bin/bash /usr/local/ispconfig/server/server.sh
root 6574 0.0 0.2 25244 7892 ? S 23:57 0:00 /usr/bin/php -q /usr/local/ispconfig/server/server.php
root 6592 0.0 0.0 2500 1012 ? Ss 23:58 0:00 /bin/sh -c /usr/local/ispconfig/server/server.sh > /dev/null 2>> /var/log/ispconfig/cron.log
root 6594 0.0 0.0 2508 1088 ? S 23:58 0:00 /bin/bash /usr/local/ispconfig/server/server.sh
root 6596 0.0 0.2 25244 7892 ? S 23:58 0:00 /usr/bin/php -q /usr/local/ispconfig/server/server.php
I removed the 'lock control' function of /usr/local/ispconfig/server/server.php and that's solves my problem.
Apparently all process of ISPConfig stopped in this function but MySQL functions (DNS records, FTP-user, Add Clients, Change some config's etc) on Web Interface works fine, so what do you think about this?
Thanks again!