First of all, if you are using an email marketing system already, you're likely in great shape. From my perspective, 90% of the benefit comes from using one at all, so don't worry that you suddenly have switch if you happen to be using a different solution. The 1/2 dozen or so that I am familar with are all mature and include the primary features we all need:
During my seven years of leading and managing a national sales organization, my team and I often talked about wanting an "excuse" to call on a prospect or a customer. As a sales person one often feel like a nuisance -- like you are looking to take more than to give. I had a flashback recently when working with one of my clients -- we needed to "tee up" situations that would allow my client's sales rep to touch base with current clients.