Views:
Question:
How can I change the file name of an attachment when it's sent from a Workflow's Email Send step?

Answer:
To change the file name, change the value from the Index field that has been set as the Document Name. Changing the field before the email send step will use the index field as the updated name.

Please refer to KBA-36738 to check whether an index field has been configured as the Document Name.

KBA is applicable for both Cloud and On-premise Organizations.