I've looked through the product docs, and I don't see any explanation of what the colors mean in the marketing calendar? In the product docs, I see orange entries, gray, and red/maroon/purple. In my own marketing calendar, the entries are all orange. What do the colors mean?
Orange means an approved campaign. Grey is a tentative campaign or email. the rest of the colors are set by you in the admin window. Go to admin > Tags > Calendar EntryTypes