spoolfile and move clarification

[zhang zhengquan <zhang.zhengquan@xxxxxxxxx>]

Dear mutt community,
here is a snippet of my muttrc

set spoolfile=+inbox
set mbox=+inbox
set mbox_type=Maildir
set folder="~/.muttmail"
set move=yes

since spoolfile and mbox are the same folder and move=yes,
what is the meaning of move=yes in this situation?

I copied this snippet from another user's rc and would like to
understand the pros and cons of this setup,

Thanks,
-- 
Zhengquan