I researched several ESPs and negotiated our email contract with one of them.  To some degree, seeing that a company had established customers was important when I was trusting something as critical as our companies email to them.<p>You need to find a way to reduce risk and the overhead of integration.  Even basic integration of a new ESP is a PITA, mostly because there is either engineering work involved, or some degree of lockin because of marketing automation that can&#x27;t be easily exported.<p>You might in fact need to offer a free year or something to convince them to invest in you and take a risk.