Campaign email - unsubscribe message

V 7.8.2. Campaigns are delivering perfectly, but as my installation is on a local machine, not a website, recipient attempts to unsubscribe fail. I would like to replace the default generated message, “To remove yourself from this email list click here,” with “To remove yourself from this email list please reply with ‘Unsubscribe’” (or something similar).
Where to change?

Based on a very quick search i would say this is what you need to look at:✓&q=TXT_REMOVE_ME&type=

Note that whatever you customize in this file will be overwritten when you upgrade to 7.9., which contains many changes in Email code.