Duplicate Calendar Events

[lago]

I am maintain a workplace which run Office 2002, 2003 & 2007.
We run an exchange server (Exchange 2003).
Recently some users have been randomly getting duplicate appointments.

User A (Owner); User B (Delegate of A); User C (Owner); User D (Delegate of C)

User A sends out a meeting request
User D accepts, Users A,B,C,D get 2 identical meeting request in their
calendars.

Repeat process, only 1 meeting in their calendar.

As this event is completely random, any user could accept and duplicates may
occur.

Any assistance would be appreciated, if my description isn't clear, I am
happy to elaborate.

Regards,
Lago

 

[TechieBird]

Hi Lago

Two questions...

1) which, if any, of these users are in Cached Exchange mode?
2) did the organizer invite a distribution group that they're a member of
(i.e. invite themself)?

 

[lago]

Hello again,

1. All users are using Cached Exchange Mode
2. All users are individually added to the meeting requests.

Regards,
Lago

 

[TechieBird]

If you temporarily put them all into Online mode is the problem still
reproducible?

Also, do any of these users have any calendar sync software to a device or
service e.g. to a PDA or Web calendar?

 

[lago]

I haven't been able to personally replicate it.
But I know I would never get the opportunity to get all the affected users
to take off Cached Mode for long enough.

Yes, about 5/8 affected users have Blackberry devices, which run off the
internal blackberry enterprise server.
I would have even less chance to test with their blackberry devices than I
would with the Cached Mode request.

Not sure if I made this clear enough in the beginning, but this problem has
only started when we introduced Office 2007 to some of the currently affected
users.

 

[TechieBird]

Interesting stuff... is there a small group of users who typically schedule a
lot of meetings between them, e.g. two managers and delegates who work
closely? It could be worth trying with them in online mode, or even
re-creating their OST files one evening to see if this helps.

See if you can spot any patterns in when this occurs, e.g. does it happen
most often when Jane is invited, or after Bob sends an update? Do these
users have any add-ins different to the rest of the group? If there are
particular users this seems to be associated with more, try rebuilding their
OST file or even recreating their mail profile.

Another thing to check is that your BES servers have the correct version of
CDO.DLL installed. I'm way out of date with what that should be, but someone
on the Exchange communities will no doubt be able to tell you. CDO version
mismatches are a classic cause of duplicate/missing appointments, although
AFAIK it's nothing like as bad as it was a few years ago.

If you fancy doing some really in-depth detective work you could use a tool
like MFCMAPI or MDBVU (not for the faint-hearted) to examine the trail of one
of these appointments. Look at the PR_OWNER_APPT_ID field for the original
invitation message, the calendar items, the 'accept' messages etc. in each
user's mailbox. (Yes, it's time-consuming. I've done it many times myself.)
It's possible the duplicate came about when a message-type item (invitation,
update or response) got a different PR_OWNER_APPT_ID - I think this is what
Outlook uses to decide what meeting an update or response belongs to. If it
doesn't match an existing meeting then Outlook will think there's a new item
needs creating. Your Exchange admins may also be able to help with this part
by examining the message tracking logs. If you can work out where/when the
problem first occurred on a particular appt, your BES guys may be able to
find something in their logs.

Of course there could be something much simpler going on that I haven't
thought of, so if anyone else has any other ideas... )

 

[lago]

I have taken the core group of users off cached mode; the only noticable
difference is that everyone complained about how slow their outlook was.
I'm absolutely certain it is because their outlook is filled with too many
old emails, but since I have no say in email policy, I ignore those
complaints.

Either way, taking them off cache mode did not solve the problem, they still
claim to be getting the duplicate appointments.

As for the BES servers, there are plans to install a new server with new
updated software, hopefully that may resolve certain other issues.

I will continue to post as I get new information.

Thanks for the advice so far.
Regards,
Lago

 

[TechieBird]

Sounds like they're better off going back to cached mode then.

It's a shame we weren't able to get to the bottom of this, but maybe an
up-to-date BES server will sort things out. Like I say, this *used* to be a
major cause of calendar problems like the one you described, I just hadn't
seen so many lately...