failue to send mail after created a new database

[hksim]

new install, debian etch, nightly build 10/14/2008
system run well after installation.
system send out system email for every operation on the web such as switching between admin and reseller.
when i create a new database for the first domain, the system failue to send any email. delete the domain which i just create, the system will send out the email again. possible bug in somewhere...