Thanks Mandar, I read up some more on the wiki, and the consensus seems to be 'why not just use 'isMemberOf' as you said.

This is the error I am getting.

org.mozilla.javascript.EcmaError: Cannot convert null to an object.

  Caused by error in <refname> at line 6

  3:  

  4: var from = gs.createUser(email.body.from);

  5: gs.log("***Inbound Action from - " + email.body.from);

==> 6: if (from.isMemberOf('ServiceNow Administrators'||'IT - ServiceNow Support')){

  7:

my script is:

s.include('validators');

//var from = email.from;

var from = gs.createUser(email.body.from);

gs.log("***Inbound Action from - " + email.body.from);

if (from.isMemberOf('ServiceNow Administrators'||'IT - ServiceNow Support')){

              current.assignment_group = "33194bd90a0a3ce00100f0f13b5f845e";

              current.assigned_to = email.from;

              current.state = 1;

              current.contact_type = "email";

              current.short_description = email.subject;

              current.insert();

              event.state="stop_processing";

      }

Once again, many thanks for your help. Mark