tell (current date)
set {monthString, yearString} to {its month as text, year as text}
set tt to "" & day & " " & monthString & " " & yearString
end tell
tell application "Mail"
if not (exists mailbox yearString) then
make new mailbox with properties {name:yearString}
say 1
end if
if not (exists mailbox monthString of mailbox yearString) then
make new mailbox with properties {name:yearString & "/" & monthString}
say 2
end if
if not (exists mailbox tt of mailbox monthString of mailbox yearString) then
make new mailbox with properties {name:yearString & "/" & monthString & "/" & tt}
say 3
end if
end tell