Dolores A Rowe asked: ...

They would like to know if there is a setting so that the email would print out the diff in the email, rather than them having to select the link to see the diff ??

There is no setting, but there is an extension I wrote to perform such a task. Here's an introductory article:

http://blog.endpoint.com/2016/03/mediawiki-extension-emaildiff.html

The extension itself:

https://www.mediawiki.org/wiki/Extension:EmailDiff