envelope icons

[FoxHillGardener]

Hope this is in the right place, but can someone direct me to a key for the different types of envelope icons you get down the left hand side of the thread list; red, ones, blue ones, ones wth little arrows etc... I'm guessing the one with the padlock is locked , but not sure about the rest

And also, in the list of forums, why are some sqares on the left green and some orange?

[FoxHillGardener]

I still wasn't seeing them and then I realised, I always go to the New Posts link in the green bar. Since that's a search the key doesn't show up, but when I went in through the forum pages proper there they are! Now don't I feel stupid

[yoanbob]

I still cant find the envelope key, only the one for the green and orange boxs