I feel like there's a fine line there that a lot of providers don't get. I am the type of person who reads every single email in my inbox, and I also don't mind subscribing for updates on things.... when those make sense. A service that honestly emails me from time to time when they release new versions or add new features is valuable to me and will keep getting its emails delivered to my inbox, and probably see a high clickthrough rate. A service that, like most, feels the need to email me at least weekly with pointless articles? No.