An entryid is a permanent unique identifier for an object in a MAPI
provider. The generic format is:

	typdef struct {
		BYTE abFlags[4];
		BYTE ab[];
	} ENTRYID;

Exchange ENTRYIDs returned via WebDAV will always have all the flag
bytes set to 0. The format of the data after the flags is
undocumented. But here's what we know...

Following the flags, Exchange ENTRYIDs have a 16-byte UID that tells
what sort of thing it identifies, then data specific to that type.

EXCHANGE SERVER - 38a1bb1005e5101aa1bb08002b2a56c2
  I've only ever seen this as the prefix to the lpStoreEntryId in a
  OP_MOVE/OP_COPY rule action. It is followed by:

		00 00
		"EMSMDB.DLL"
		00 00 00 00


MAILBOX STORE - 1b55fa20aa6611cd9bc800aa002fc45a
  Identifies the mailbox. Can be found as the PR_STORE_ENTRYID
  property on any folder in the mailbox. It is followed by 4
  apparently constant bytes, the Exchange server name (capitalized and
  NUL-terminated), and the Exchange 5.5 DN of the mailbox owner (also
  NUL-terminated)

		0c 00 00 00
		"SHREWDNESS\0"
		"/o=XCS/ou=First Administrative Group/cn=Recipients/cn=danw\0"


PUBLIC FOLDER STORE - 1c830210aa6611cd9bc800aa002fc45a
  Identifies the public folder store. The format is the same as for a
  mailbox store, except that the constant is different and there is no
  DN.

		06 00 00 00
		"SHREWDNESS\0"


DATABASE OBJECT (FOLDER/MESSAGE) - [UID varies per store]
  Unique to each folder and message(/contact/appointment/task). For a
  folder, the UID is followed by "01 00" (in a mailbox store) or "03
  00" (in a public store), the folder's 22-byte PR_SOURCE_KEY, and 2
  zero bytes. For a message, the UID is followed by "07 00" (in a
  mailbox store) or "09 00" (in a public store), the message's parent
  folder's PR_SOURCE_KEY, 2 zero bytes, the message's PR_SOURCE_KEY,
  and 2 more zero bytes.

  An object's permanenturl is generated from its ENTRYID (specifically
  from the PR_SOURCE_KEY part):

     PR_ENTRYID:
	00 00 00 00 1a 44 73 90 aa 66 11 cd 9b c8 00 aa    .....Ds..f......
	00 2f c4 5a 03 00 50 2d 6a fd 16 1e f2 43 89 95    ./.Z..P-j....C..
	e1 d9 29 cf 92 eb 00 00 00 00 00 32 00 00          ..)........2..

     http://schemas.microsoft.com/exchange/permanenturl:
	http://shrewdness.xcs.ximian.com/public/-FlatUrlSpace-/502d6afd161ef2438995e1d929cf92eb-32


ONE-OFF RECIPIENT/DISTLIST MEMBER (812b1fa4bea310199d6e00dd010f5402)
  Used to identify a "one-off" email address (ie, one that does not
  correspond to any Contact or GAL entry). See
  e2k_entryid_generate_oneoff in e2k-utils.c for more information


CONTACT FOLDER RECIPIENT (fe42aa0a18c71a10e8850b651c240000)
  Used to identify a recipient that came from a Contact folder. See
  e2k_entryid_generate_contact in e2k-utils.c for more information


GAL RECIPIENT (dca740c8c042101ab4b908002b2fe182)
  Used to identify a recipient that came from the GAL. See
  e2k_entryid_generate_local in e2k-utils.c for more information


CONTACT/GAL DISTLIST MEMBER (c091add3519dcf11a4a900aa0047faa4)
  Used to identify a distlist member that came from a contact folder
  or the GAL. Followed by "b5" (for a GAL entry) or "c3" (for a
  Contact folder entry), followed by a contact folder or gal recipient
  ENTRYID.
