Exchange active sync issues for mobile phone users on SBS2003

Users within a department of a business using SBS 2003 with Exchange 2003 are having an issue with their calendar events disappearing.
There are about 10 users within the department, but only the ones who have Exchange mail and calendar on their iphone4 are having calendar issues.  Error in the server logs also shows up for each affected user:

Event 3005
User:  department user with calendar event deletion issues
Unexpected exchange mailbox server error.  Status code 500.  Verify the exchange mailbox server is working correctly.

Is there a way to safely resynchronize these users?  I believe there is a setting in their OU for enabling and disabling activesync.   Will removing their accounts from their phones and then somehow resetting their connection clear the issue?  They will need the calendars to be re added to the phones as soon as possible as they work out of the office a lot.

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A few things to confirm:

1)  You do need to make sure no GPO or anything else is causing the exchange features for activesync to be enabled and disabled (or flopping back and forth).  If that is happening, get that resolved before setting the phones up again.

2)  Corrupt calendar appointments can cause unpredictable results while synchronizing calendar events.  I've been involved in troubleshooting a ton of mobile device calendar synchronization where the calendar was not receiving nearly all of the events.  It was not always possible to identify a trend, that is "anything after X date is not synchronized".  The way I handle this is I export all of their calendar data to a PST.  I then create 2 additional calendars in the users mailbox and import the calendar data to both calendars.  In one of the calendars, I delete the first half of their appointments.  In the second calendar, I delete the other half of the appointments.  I then set their phone to synchronize these calendars and see if both calendars sync all of the items.  Usually what happens is you have one of the 2 calendars sync just fine, while the other one does not.  Either way, you continue the process splitting the data up in halves to eventually identify the bad item.

Another way you can TRY to accomplish this is to export all of the items to a CSV file, delete all calendar data, then reimport the items into the calendar.  This procedure can sometimes correct calendar data, but does not always work.  It certainly is faster than the procedure explained above.

I will be the first to admit that iOS in particular has an extreme lack of helpfulness in identifying activesync issues.  There are absolutely no logs to reference.

As for the messages in the logs referring error 500, go to and test connectivity to the user mailboxes having issues.  You can perform a mock synchronization of the items and see if they identify any problems.  I've seen a lot of these errors previously at our front end server, though the users don't necessarily see an issue from their devices, so I'm not 100% convinced they are related to your problem.

If all of your users on the exchange server get error 500, you can follow this article for rebuilding the virtual directories.
AE_JBAuthor Commented:
The problem is limited to the 5 users within a 10 user department who use their exchange account on their iphones.  All members of the department share calendars within outlook.  The rest of the 40 person organization does not have any issues, except for one HTC user in another department who does not share calendars, This user has had similar, intermittent, activesync issues in the past.  This being the case, I would not want to rebuild the the virtual directories, since other 10 or so smartphone users on the domain have no issues.

I'll run through options you outlined.
One thing to keep in mind with Exchange 2003 and activesync (mostly applicable to mail folders, not calendars).

There is a limitation within exchange 2003 that doesn't play well with ActiveSync when you have a huge number of items in a given view.  A view is defined as a single folder.  For example, a folder inside of the inbox would be considered a view.  If a folder contains more than 5,000 items, archive or move some of those items out until you're around 2,000 items.  Like I said, this is rarely impacting the calendar, because you generally have less items in your calendar than you do the rest of your mailbox, just a bit of info for you.  The symptom to this problem would be a user saying "I can sync most of my folders, but one particular folder won't sync" and you see a large number of items in the broken folder.

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Alan HardistyCo-OwnerCommented:
Please check your IIS settings using my Exchange 2003 / Activesync article and if there are any differences, please let me know what they are before changing anything.

Incorrect settings can cause issues with syncing.

Another issue could be the version of Massync.dll on your system.  Please check if the version is version 6.5.7654.7 or higher:

I can give you a link to the hotfix if you want it and don't want to call MS to get hold of it.

The settings Alan has listed I would follow only if you had a large number of users experiencing issues with all items synchronizing.  When you're dealing with particular folders/views (like the calendar), you can pretty much rule out issues within IIS.
AE_JBAuthor Commented:
Thanks.  I am going to start back at the beginning, starting with isolating the problem to either the phones or the server.  I will run a connectivity test to the phones.  I will also check that the default calendar on the phone is set to exchange.
If any of these settings are out of place I will resolve them before looking to the server.  I will re add the exchange profile to the phones and test calendar entries to, and from, the phones.
If there are still sync errors, I will then focus my attention to the server and Exchange, and continue with the suggestions above.
I re post if I have specific questions at that point.
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Windows Server 2003

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