Whenever I tried to use zmlmtpinject to import some message into a mailbox, I get a failed message. Then zmcontrol status shows that mailbox service has been stopped.

Checking the zimbra.log file I see the following

tail -f zimbra.log
2005-10-15 06:06:48,529 FATAL [LmtpServer-1] [] system - Fatal error occurred while handling connection
java.lang.OutOfMemoryError: Java heap space

Right now the test machine I have zimbra installed on has 512 MB of RAM. I thought this meets the minimum requirement for zimbra. Please help.