Mailchimp's slogan is that email marketing is so simple even a chimp could do it. That may have been the case a few years ago, but not today. Today you really need to think about how email marketing fits into your business in order to increase your sales. They do not have nearly as many features that help you do this as our ecommerce plugins do. Their ecommerce plugins will capture a customer's email into a specific list and tell you how much in sales a newsletter generated but that's where the profit increasing potential stops. Sales are credited to your email for 30 days after a recipient clicks a link which is wildly inaccurate. Their plugin model is also flawed because it "pushes" data from your store into MailChimp during the customers checkout process. This means that it adds a delay to your customers checkout process while it "pushes" data in MailChimp. If there's a network problem the sale is not reported, the customer is not captured and an even longer delay is imposed... and we've seen MailChimp go down for very long periods of time.
Even MailChimp's customers wish they had our capabilities. Plus they only provide support via email during normal business hours. We provide a high level of support 24/7 via email and during normal business hour via phone. Finally, if you want surveys or just to see who opened your newsletter then you're going to be paying extra. You'll also be paying for the same subscriber every time that same email is in a different list. In summary, Mailchimp's ecommerce plugins lack the features needed to increase your sales, they provide innacurate sales reports and worst of all can cause problems during checkout.
iContact's slogan is "Email Marketing Simplified" and it's true. It's so simplified it lacks any integration with your store. We can stop right here. In summary, iContact has no ecommerce integration to help you increase your store sales.
ConstantContact's slogan is connect, inform, grow. Their emails are delivered from a shared pool of IP addresses which means that the behavior of any other client will affect you. That in turn means they are extremely particular about you affecting other customers. They will kick you off their service if you do not keep an absurdly low unsubscribe and complaint rate. We've had customers come who've been kicked off their service during the busiest season for high spam complaints, even though they are following all best practices. The ecommerce plugins are out there, by third parties. These plugins are limited and so is support. In summary, ConstantContact's ecommerce plugins are written by third parties, are not supported by them and lack the potential to increase your sales. On top of that they may kick you off their service during your busiest time of the year.