Is there a way to add information to the reunion registration details that is sent to each person?

For example I would like to add a few words to encourage the folks to donate to our fund raising efforts.

Thanks,
Ian

Not currently no, that's really just a typical receipt email. You can easily click on Email The Class and email only those who have signed up to attend the reunion though. Not quite as automated as what you're looking for, but the best solution available.