Features of Hey
"Hey describes itself as a "full email service provider" with a few key features.": Let's look at them.
"You have to approve senders, who until then are listed in a "first-time senders" section. If rejected, subsequent emails go directly into a spam box.": So I have two sections. Emails from people I know and other ones. And, just like most other clients, there's a button to block the sender. Good to know.
"You can enable a sender to bypass the quarantine by giving them a code; these can be regenerated to prevent leaked codes causing trouble.": So if I understand this correctly, I'll be talking to someone else who wants to email me. I'll give them my email address, but then I'll also have to say "Wait a minute. My email is paranoid and will block you so I'm going to generate a number on my phone. Please put that number into your email in some place, I'm not really sure, and you'll bypass my system's filters". This is somehow more difficult than just going to see them in the first-time senders box?
"The inbox is renamed the "Imbox" on the basis that anything that makes it is Important.": Maybe it's just me, but that sounds childish.
"File attachments that you send are not included with the email, but sent as links to files stored on Basecamp's servers.": So it triggers spam filters that see a link to an unfamiliar server, huh? And it probably tracks people who access my attachments, exactly when or how many times, etc. The attachments don't get autostored on my recipients system like they usually do, so they might try to access it later only to find the server's deleted it. If I want to send them a link, I'll upload my own file somewhere I control, thank you very much.
"You can rename or merge email threads;": Sounds handy. I assume this is retroactive, not just what I can do during a reply. Maybe a useful feature.
"and email trackers, which tell the sender when you opened the message, are mostly blocked. "We bulk strip everything that even smells like a spy pixel,": Good job. How does this compare to the don't-load-remote-content feature on mail clients?
"In addition, all images are routed through the Hey servers so that the recipient's IP address is never revealed.": This is a nice privacy feature. I already have it by not loading the content, plus there are other mailservers which already do that.
"No automated signatures or footers are allowed." ... "The email already says it's from you. If someone needs your phone number, they can ask,": I'm restricted in what I can put into my own emails? Not that you strip the signatures from incoming emails when I wouldn't want them, but you strip them out of my own emails? Do you understand what user choice is? If I want to have a signature that gives someone alternate methods of contacting me in an emergency, or other people who might be better able to handle their question, I certainly will and getting in my way is ill-advised.
"The system does not show numbers of unread messages as this is an unnecessary distraction.": Or it's a method of finding out if you have new emails without the notification sound turned on. If you leave any messages unread, a flag will be up, and if you get some new ones, the number is higher. I can see it at a glance.
"Notifications are off, though you can enable notifications for specific senders or threads.": This is nice. I don't know many mail clients that allow me to tailor my notifications by specific message characteristics. I'd also like it if I could set different sounds or vibrations for that as well. That's a feature worth having.
"Attachments are filed automatically in an attachment library.": I'm not sure exactly what this means, but if it's just a window to see all attachments, why not.
"A "Reply later" folder lets you store emails for attention at another time – better than the common technique of marking an email unread, according to Basecamp.": Create any extra folders you want. I can do that too.
"Another feature is the ability to expand all unread emails in a single action so you can scroll through without opening each one individually.": I don't need that, but I can see why someone might.
"There is also a technique for managing frequent senders: you can bundle all their messages together so "they'll only take up a single row in your Imbox.": Possibly useful feature.
This looks like four useful features, five detrimental features, and three neutral features that are already possible. I have a suggestion for you guys. Ditch the server part. That's where most of your detrimental features are. Just implement a mail client program with the features you like, which includes all of the useful ones, and we can look at getting it later. No annual fee, perhaps, but maybe people will agree to buy it. I'd try to be less heavy-handed with your preferences, though.