The support team at Datacaptive are very responsive and helpful, they have helped us over the last few years with our email service provider needs.
They also provide some good software products as well. I've had nothing but positive experiences with them. Nothing in particular about this product has stood out yet! We use their Email Service Provider platform to send emails from multiple domains (our own plus others) all across North America - so being able to centralise it within one account makes sense.