Check your "/etc/postfix/mysql-virtual_*.cf"
files and double check that the "mail_admin"
are identical in all of them.
the files can be found here:
should also be the exact same in these files:
make sure there are no blank spaces after them ( except for /etc/pam.d/smtp ) and upper and lower cases, numbers, hyphens, etc. match exactly.
any small typo will cause the system problems.