 MS example shows how mailslots can be used for interprocess
(one way) communication on local machine as an alternative to
SendMessage(,WM_COPYDATA,,) used in WM example.
 In the MS way there's no need to call user functions (saves memory
and resources), it is pure kernel thing (no windows, suitable
for spy dlls). Nice fact is that ReadFile can wait for mailslot
input (contains internal call to WaitForSingleObject) like it can
wait, for example, for console input and like GetMessage waits for
a message. Also mail size is determined by ReadFile automatically.
 Examples work on both 9x and NT. 9x implementation of mailslots
isn't good. GetMailslotInfo returns in some buffers trash and,
for example, cbMessage is returned as WORD instead of DWORD.
Also mailslot size is limited; if the size is too large, WriteFile
can succeed, but the message is lost somehow. Experimental maximal
mailslot size (max. message size) is ~4093 in 9x. Between WriteFile
(client) calls should be some delay when sending long message (9x),
otherwise the message can be lost. Examples can be optimized for NT:
remove max. message size and remove sending long messages per partes.
 MS example is not as fast as WM example, when sending long message
because of 9x delays (Sleep). On NT without delays is the MS-WM speed
difference indistinguishable. Disadvantage of WM is that SendMessage
has to wait for finishing processing in server, hence client's thread
is not responsive for that time.