Do PostMessage() messages appear in order in Windows?

Question

The general question, is if I post several messages to the windows message pump from a separate worker thread, will they appear at their destination in the order I sent? ie..

::PostMessage(m_hUsers, WM_BULKPROCESS, 0, 0);
// ... some processing here ...
::PostMessage(m_hUsers, WM_BULKDONE, 0, 0);

m_hUsers is a handle (HWND) to a window I'm sending the messages to from my worker thread. So, will WM_BULKPROCESS always show up first in the window (and therefore be processed by the handler in that dialog class), or is it possible for them to get out of order, ie WM_BULKDONE gets processed before WM_BULKPROCESS, even though it was sent last?