The app "Email Listmaker" can be found at http://emaillistmaker.com and is a free tool for scanning content for email addresses. You can copy & paste from Excel, Word, or any other file you want to extract all of the email addresses from. The list output gives you an email list free of duplicates or incorrectly formatted email addresses and you can control the format of the list.

I originally created this app for volunteer coordinators that were keeping their contacts in various file formats. They needed a list emails from those documents they could copy and paste into an email app. I've rewritten it from its original form to be web friendly so even more people can use the tool.