Check out Zimbra yet? They have open source and enterprise solutions. http://www.zimbra.com/products/pricing.html http://www.zimbra.com/products/pricing.html

Check out Zimbra yet? They have open source and enterprise solutions. http://www.zimbra.com/products/pricing.html http://www.zimbra.com/products/pricing.html Also look at Fastmail options. https://www.fastmail.fm/signup/business.html https://www.fastmail.fm/signup/business.html I'd call / email to negotiate prices with them. Why pay what's just listed on their site? If your users are mostly hands-off in terms of support maybe getting a discount is feasible.