To explain our set up.  We have multiple "regions" across the world, each with their own Service Desk group (which are separate to each other in terms of technicians, location etc)

As an example, our Default Settings cover all of our sites in the UK.  We have a UK helpdesk address (that autoforwards into ServiceDesk+). Under the default settings we have a Business rule that checks whether the requester emailed the UK helpdesk address. If they did, the ticket gets assigned to the UK Helpdesk Group for 1st Line troubleshooting etc.

We also have an office based in Stamford in North America. They also have their own local NA helpdesk email (which is different to the UK one, but still autoforwards into ServiceDesk+). Again, a business rule checks whether the user emailed the US helpdesk email, and then assigns it to the NA Helpdesk Group (seperate to the UK one above, and only visible to requesters with Stamford as their site). 

This works fine on a day to day basis, but it breaks with requesters with external email addresses. We often get external emails from Vendors, or internal users who are off site and unable to log into their work email, so using a personal address

If they email the UK Helpdesk address, there is no problem.  As this is part of the Default Settings, it knows what to do with the ticket, and assigns it to the UK Helpdesk group.

However, if they email the NA Helpdesk address, as there is no site configured for this external requester, it will again check the Default Settings.  The NA Helpdesk address is not in the Default Settings business rules, so therefore it does not know what do with the ticket.  It ends up with Group = None (eg: not assigned to any group)

I thought I might be able to fix this by adding a business rule under the Default Settings that checks for NA email address, and then assigns it to the NA Helpdesk group.

This doesn't work, because the only Support Groups I can see to assign to under Actions, are the ones associated with the Default Settings (NA Helpdesk is not available under this, and we don't want it to be as it's an entirely separate team/location)

I had the idea of setting up an Incident template that sets the site to Stamford, and the Group to NA Service Desk

Next I set up a business rule in the Default settings that checks if the NA helpdesk email address is used.  If it is, it will apply the above template, effectively redirecting the ticket to the NA Helpdesk.

I tested this by emailing the NA helpdesk from my external email.  The ticket logged successfully, however when I check it I saw this:

So you can see, it has applied the template, however it hasn't set the site or support group.

Am I going about this the wrong way, or is there something wrong with my template or business rule?  

(I have managed to get it to work in a way, but it involves ticking "Override request values with Business Rule values" in the rule.  This applies the template correctly, and routes it to the right group, however it results in me receiving the "Your ticket has been logged..." autoresponse from ServiceDesk+. We don't normally send this to external people and would prefer to keep it that way.  I'm assuming because it's applied an internal site to the Requester, it therefore treats them as internal)

Is there any other way I can do this? Perhaps a custom script in the Form / Field rules?

Version;  9.3 Build  9326