Note: The System Matrix entry is E-Mail Subject not Email Subject. If you use the latter it will not work.
It is relatively straightforward to amend this, you will need access to System Matrix and Database Maintenance.
Amend phrase
To amend the phrase used, please follow the below steps:
Open System Matrix.
Select the case type from the drop-down that you want to amend.
Locate the field E-Mail Subject.
If this exists, make a note of the field it refers to.
If it does not exist, then don't worry - this can be added in.
Open Database Maintenance.
Locate the existing field on the case type you are amending or create a new one as a maths field.
Open up the maths editor by clicking on the jigsaw.
Set up the maths
You are now setting up the maths to determine what you need in the email subject lines:
An example is: result = {case.key} + "/" + {Matter Description.Text}
Amend the data to the information you wish to be held by the subject line, and then click save. Follow the steps below to set it up within the System Matrix:
Repeat steps 1 and 2 from the initial instructions.
If the field does not exist, you will need to create one named E-Mail Subject by clicking New.
Select the field by pressing the tab key.
Select the database field you created/amended before.
Click Save.
This is now set as the default E-Mail Subject line.