+ def list_domains_users(domains)
+ usernames = []
+
+ # Just assume PostgreSQL for now.
+ begin
+ connection = PGconn.connect(@db_host,
+ @db_port,
+ @db_opts,
+ @db_tty,
+ @db_name,
+ @db_user,
+ @db_pass)
+
+ sql_query = 'SELECT username FROM mailbox WHERE domain IN $1;'
+
+ connection.query(sql_query, [domains]) do |result|
+ usernames = result.field_values('username')
+ end
+
+ connection.close()
+ rescue PGError => e
+ # Pretend like we're database-agnostic in case we ever are.
+ raise DatabaseError.new(e)
+ end
+
+ return usernames
+ end
+