Evaluating usability at an ESP

Clients and random people often ask me to recommend an ESP based on “the best delivery.” I usually point out that most of the reputable ESPs are similar in terms of their delivery. There aren’t many widely used reputation services that block based on ESPs unless there is long term and ongoing problem from the ESP.
This is even more true when the ESP uses dedicated IPs for customers. ESPs that use shared IPs can have poor delivery if they don’t effectively police customers and lower the reputation of all their IP addresses.
My normal comment about ESPs is to find a price point and feature set that meets the client’s needs. Clickmail has a good post about how to evaluate an ESP for usability.