So you would like to change the name of the auto-responder of your support manager? You can do it by editing the following two lines in two files. Please note this may be over-written when updating.
In: /plugins/support_manager/language/en_us/client_tickets.php
Find: $lang['ClientTickets.reply.system'] = "System";
Change System to whatever you would like.
In: /plugins/support_manager/language/en_us/admin_tickets.php
Find: $lang['AdminTickets.reply.system'] = "System";
Change System to whatever you would like.