With zabbix_server running, if mysql user "zabbix" privileges or password change, drop, or are somehow affected, zabbix_server dies silently.

It should still email to user group set in "User group for database down message" under "Administration --> General --> Other"

How to reproduce:

With zabbix_server running, connect to mysql, and change password for 'zabbix' user:

mysql>use mysql;
mysql>update mysql.user set Password=password('anydifferentpassword') WHERE User='zabbix';
mysql>flush privileges;

in zabbix_server.log:

25085:20100108:185838.859 [Z3001] Connection to database 'zabbix' failed: [1045] Access denied for user 'zabbix'@'localhost' (using password: YES)
25085:20100108:185838.869 One child process died (PID:25118). Exiting ...

And no email to zabbix administrators sadly.