How to add a name field into Email Subject when bulk sending envelopes

Hi, I’m seeking information on how you customise the Email Subject to include the customer name when creating a bulk send. I understand how to do this for individual templates (and are using successfully), but am not having success adding into the bulk send template.

The reason is that signed agreements will come into a Shared Mailbox, and I need the multiple users to be able to easily identify which customer the envelope is from (without opening). 

I have read the related articles in the DocuSign support material and watched numerous Youtube videos, but none address this. Is there specific data you need to add into the CSV file to get this to work. 

Thanks in advance.

Patricia