Better search features. Ability to search with Boolean - for emails with or without attachmenents - or if responded to
search right now is really bad. I use the native apps or other programs to search emails even though your program is my go to for email both in iOS and mac. Search needs to be best in class. Even if you do a local index of all the emails so that you can bring up emails immediately. Given that few people are using folders searching is everything now. Furthermore to be able to list emails if they have been responded to or not is vital.