NOTE FOR ADMINS UPGRADING FROM 2.0.X -> 2.2.X :
	*) Update database using a script
	   %%DATADIR%%/mysql/migrate_from_2.0_to_2.2.mysql or
	   %%DATADIR%%/postgresql/migrate_from_2.0_to_2.2.pgsql
	*) Run `dbmail-util -by'
	*) Edit configuration file
	   `[DBMAIL]' section must have `driver=mysql/pgsql' and
	   `authdriver=sql/ldap'.

NOTE FOR ADMINS UPGRADING FROM 2.1.X -> 2.2 :

	*) Update database using a script
	   %%DATADIR%%/mysql/2_1_7-2_2_0.mysql (if you're using MySQL)
	   %%DATADIR%%/postgresql/2_1_7-2_2_0.pgsql (PostgreSQL)
	   %%DATADIR%%/sqlite/2_1_7-2_2_0.sqlite (SQLite3)
	*) Run `dbmail-util -by'