Curious how this compares with Interspire (<a href="http:&#x2F;&#x2F;www.interspire.com&#x2F;emailmarketer&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.interspire.com&#x2F;emailmarketer&#x2F;</a>). I set that up a couple of years back to use with our Sendgrid account and we had great results.