Corporate IT problems with email verification software?

What are the ramifications of mass email verification software in a corporate IT environment? One of our departments wants to clean an email list of 65,000 addresses with a product like G-Lock Software’s Advanced Email Verifier.

http://www.glocksoft.com/amlv/

Depending on how the software actually works (disregarding the marketing hype) I can think of a few potential problems. What’s your take on this? Thanks.