[dddw]

Use to maintain a couple of mailservers for an ecommerce platform. The amount of times we where greylisted by MS was so often. They actually have good tools at MS to check is your are blacklisted, but the greylisting was horrible. Resolution was always to request to be un-blacklisted at live, hotmail, and outlook. Never confirmation you actually where blocked, but problem was always fixed in half a day after that.