I've been using Mailbox for a while and the only thing it's really helping me with is the ability to either archive-or-delete, which none of the other clients can easily do.

My main problem is that with my style of thinking, I'll get an email that will make me think, "Yeah, I want to do something about that... later." But not "later" in terms of a calendar date - "later" in terms of when I am enabled to work on it, as in when a blocking dependency disappears. I can't find an easy way to make those emails disappear until they are triggered by me completing other things I care about.