I am trying to create a validation rule that stops users from creating a case if they don't fill out a certain picklist field called "Order Type".  I only want this validation rule to apply to cases manually created by a user, and not any created by the "system" user, that is the creator of all incooming email2case cases.  I put together the rule below, thinking it would work just fine, but had pretty much the opposite effect.  Instead of skipping all of the cases created by the system user (005d0000001bgP5), it looked at all those cases and stopped them from being created, since they are auto-created by email2case and we don't have a defalut value for the "Order Type" field established, so that field was always blank and caused this error.  Does anyone know why the validation rule is not working as expected and looking at ALL my cases with this record type instead of just the cases NOT created by the user noted in the below rule?  Thanks in advance!!

And(CreatedById <> '005d0000001bgP5', RecordTypeId = '012d0000000P8Eu', ISPICKVAL(Order_Type__c,""))
 

I have a sharing rule that only allows certain asssociates to edit cases with certain record types.  When they click "Edit" on a case that is a record type they don't have write access to, they get an error, which is what we want.  However, if they try to reply to an email related to that case, they can without an issue.  How can we prevent this?

I prefer something declarative, but if that's not possible, I will use code.

We are trying to bring up another department to use case management, and they already have their own email address.  We are finding that since this department already communicates with the other department already on Salesforce using cases (Member Services), new cases are not being created.  Instead, the emails to this new department are getting linked up to the existing case already created by Member Services, since they started the case in Salesforce (establishing the thread/ref #), and the other department was added later.  The case thread ID (ex: [ ref:00DdeHLa.500dIPVHW:ref ]) was already established, so even though a new email2case address was added, it is linking up with the existing case, instead of creating a new one.
 
I read that you can turn the case thread/ref# off, but this change can’t be made by record type, so it wouldn’t work for us.  

Can anyone recommend a solution (prefer flow over apex trigger, but if apex is unavoidable, that's fine)

Thank You!

We are trying to bring up another department to use case management, and they already have their own email address.  We are finding that since this department already communicates with the other department already on Salesforce using cases (Member Services), new cases are not being created.  Instead, the emails to this new department are getting linked up to the existing case already created by Member Services, since they started the case in Salesforce (establishing the thread/ref #), and the other department was added later.  The case thread ID (ex: [ ref:00DdeHLa.500dIPVHW:ref ]) was already established, so even though a new email2case address was added, it is linking up with the existing case, instead of creating a new one.
 
I read that you can turn the case thread/ref# off, but this change can’t be made by record type, so it wouldn’t work for us.  

Can anyone recommend a solution (prefer flow over apex trigger, but if apex is unavoidable, that's fine)

Thank You!