I love Postbox. I talk about it a lot. However Postbox is trying to be more than a mail client and as part of that is attempting to sneak into the world of GTD with the inclusion of todos and topics.
Now call me old fashioned but I use Things for my GTD stuff and so don’t use todos or topics in Postbox.
“Not a problem really is it?” I hear you yell. Well no until you look at the amount of space the topic row of Message View takes up. Believe me on a small screen this matters: