Vertical Response: Email Marketing for Nonprofits (and others)

There are so many email marketing services out there: Constant Contact, Mail Chimp, etc.  Why should a nonprofit go with Vertical Response?  Because they have a free program that allows up to 10,000 emails per month and nice discounts on other services (postcards, surveys).  I'm also a fan of their marketing education library, which can be useful too.  A 98% delivery rate isn't bad either. Neither is social media integration.