Re: does Exchange provide a unique id for messages?

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Hello,

PR_EntryID may be unique, but the only way to compare two entry ids is the
IMAPISupport::CompareEntryIDs...

If you are using MAPI, that may be fine... but for other access
technologies, such as WebDAV, its pretty useless.

Greetings,
Henning Krause
MVP - Exchange
http://www.infinitec.de


"Iv Borissov" <dummy@xxxxxxxxxxxxxxxxxxxx> wrote in message
news:ugzOXMlmFHA.2152@xxxxxxxxxxxxxxxxxxxxxxx
Again, read and learn MSDN, it is easy:

FROM MSDN:

The following table summarizes important differences among PR_ENTRYID,
PR_RECORD_KEY, and PR_SEARCH_KEY.

Characteristic PR_ENTRYID PR_RECORD_KEY PR_SEARCH_KEY
Required on attachment objects No Yes No
Required on folder objects Yes Yes No
Required on message store objects Yes Yes No
Required on status objects Yes No No
Created by client No No Yes
Available before call to SaveChanges Maybe Maybe Messages - Yes
Others - Maybe
Changed in a copy operation Yes Yes No
Changeable by client after a copy No No Yes
Unique within Entire world Provider instance Entire world
Binary comparable (as with memcmp) No - use IMAPISupport::
CompareEntryIDs Yes Yes

--


Each message have PR_ENTRYID Unique within Entire world .

Because long-term entry identifiers must be unique, when a message or folder
is copied from one message store to another, it must be assigned a new entry
identifier. Service providers assign new entry identifiers to moved/copied
objects.

Iv Borissov
IMI Support Team
http://www.imibo.com/imidev/

*everything that has a beginning has an end*



"mynab" <mynab@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:407057A8-30B1-423C-83EC-9CCD189F841F@xxxxxxxxxxxxxxxx
> I believe the EntryID will change if the item is copied to another
> location.
> Therefore, it will not be 100% guaranteed unique.
>
> --
> Thanks,
> Andrew
>
>
> "Iv Borissov" wrote:
>
> > Each message have unique Entry ID. It is Extended MAPI Property. Please
> > see
> > Entry Identifiers -
> > http://msdn.microsoft.com/library/en-us/mapi/html/e76663ff-5119-4ecc-987e-c41ff7580437.asp
> >
> > Messaging API (MAPI) > Guide > MAPI Programming Basics > Entry
> > Identifiers
> >
> > --
> > Iv Borissov
> > IMI Support Team
> > http://www.imibo.com/imidev/
> > *everything that has a beginning has an end*
> >
> >
> >
> > "struggling..." <struggling@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
> > news:7CE1D808-3B31-4CB5-B42A-3E78683A9652@xxxxxxxxxxxxxxxx
> > > Hi,
> > > Is it the Message-ID header? or some other MAPI property?
> > > thanks for the help.
> > >
> > >
> > >
> > >
> > > "Iv Borissov" wrote:
> > >
> > > > Yes
> > > >
> > > > --
> > > > Iv Borissov
> > > > IMI Support Team
> > > > http://www.imibo.com/imidev/
> > > >
> > > > *everything that has a beginning has an end*
> > > >
> > > >
> > > >
> > > > "struggling..." <struggling@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
> > > > message
> > > > news:72C5DDE9-320A-4BD4-AB0B-D621F2521DD3@xxxxxxxxxxxxxxxx
> > > > > Hi,
> > > > >
> > > > > Does Exchange Server provide a guaranteed unique id for stored
> > > > > emails?
> > > > > Thanks,
> > > > >
> > > > >
> > > >
> > > >
> > > >
> >
> >
> >


.

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