procedure

1. create item

   Type : Zabbix trapper
   Key : test
   Type of information : Numeric (unsigned)
   

1. create trigger
   The conditional expression can be anything.
2. Send string with zabbix_sender.

   ]#  zabbix_sender -z 127.0.0.1 -s "Zabbix server" -k test -o "A" -vv
   zabbix_sender [4905]: DEBUG: answer [{"response":"success","info":"processed: 1; failed: 0; total: 1; seconds spent: 0.000038"}]
   Response from "127.0.0.1:10051": "processed: 1; failed: 0; total: 1; seconds spent: 0.000038"
   sent: 1; skipped: 0; total: 1
   

   The item will become "Not supported", but the trigger will remain "Enabled".
   
   

1. Send numeric with zabbix_sender.

   ]#  zabbix_sender -z 127.0.0.1 -s "Zabbix server" -k test -o "0" -vv
   zabbix_sender [4908]: DEBUG: answer [{"response":"success","info":"processed: 1; failed: 0; total: 1; seconds spent: 0.000042"}]
   Response from "127.0.0.1:10051": "processed: 1; failed: 0; total: 1; seconds spent: 0.000042"
   sent: 1; skipped: 0; total: 1
   

   The item will be "Enabled", but the trigger will be "Unkown".
   
   

I have checked versions below 5.0.17 and this behavior has been occurring since 5.0.12.

In 5.0.11, when an item becomes "Not supported", the trigger also becomes "Unknown".