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For example, there are a number of email fulfillment SaaS applications (ExactTarget, Silverpop, ConstantContact, Mailchimp - the list goes on and on)
Are specific questions regarding these services, as web applications, welcome here?
I don't see why they are off topic, since they behave like a web application. Feel free to ask questions about them, though the question should still be specific about the usage of the web application.