For domains i find Openprovider.eu is pretty cheap imo, especially if you have a lot and buy in a package it is nearly costprice. Their DNS isn't great though, good enough for personal projects but not for business, would set that somewhere else.
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.
I got a last.FM story. I used last.fm for years, then wanted tot use it again after a hiatus. But was locked out of my account, and the email I used of that service didn't exist anymore. I contacted last.fm saying what the old email was, and told them the profile picture was from a guitarist from an obscure islandic band, who's blonde hair I photo shopped into brown, so he looked more like me. They gave we a reset link. Very happy to use it again. I do wonder how they stay afloat.