ASM send mail alert when request violation with iRule

You just need to add Support_id in the log as your custom alerts looks for this. Use the below iRule it will work

when ASM_REQUEST_VIOLATION { 

set x [ASM::violation_data] 
log local3. "Support_id: Request violations:=[lindex $x 0] Support id:=[lindex $x 1] web_application=[lindex $x 2] severity=[lindex $x 3] source ip:=[lindex $x 4] attack_type=[lindex $x 5] request_status=[lindex $x 6]" 

}