Question : Activesync only downloads all emails if already downloaded to Outlook Client, otherwise intermittent emails received

Server Spec - SBS 2003 SP2, Exchange 2003 SP2
I have a few PDAs (mostly O2s XDA and UBIQUIO) with either 2003, Mobile 5, Mobile 6.   These have all been working fine sending/receiving emails via GPRS until a few weeks ago.  
The following are all working OK with Self Signed Digital Certificate
Internal Outlook clients
HTTP over RPC
OWA
OMA
The only change I can think of is I moved the Information Store to another disk, due to out of disk space.
Now when a PDA tries to sync emails, it downloads some emails, not all, but on the odd occasion it will download all.   Have tried plain text, rich text, HTML.  Have tried soft-reset and the same applies.
If Outlook client is open, and emails have been retrieved.  The PDA syncs perfectly everytime.
I have trolled the web looking for a solution, with no luck.
The only thing I have tried is http://support.microsoft.com/kb/298415 - added the registry setting and rebooted server. with no luck.
Any help would be great.
Thanks

Answer : Activesync only downloads all emails if already downloaded to Outlook Client, otherwise intermittent emails received

Hi,

I've just encountered the same problem here and stopping the Scanmail service did work.
After contacting TrendMicro about this problem they told me the problem was with upgrading from version 7 to version 8'.
The solution they gave me worked and is al follows:

This case is a defect in SMEX VSAPI module.
From the logs that you've provided, the "VirusScanProactiveScanning" keys under the
++++++++++++++++++++++++++++++++++++++++++++++++++++++
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\me>\Pr
ivate-3484c833-f074-4793-97a0-0bbbcdbb7c75]
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\me>\Pu
blic-a785d57d-8a08-44ce-86c4-04bfea4691e5]
++++++++++++++++++++++++++++++++++++++++++++++++++++++
were not removed when upgrade from 7.0 to 8.0, and cause proactive scan to turn off.
 
SMEX 8.0 does not use this key.
 
Proactive scan for Exchange store is turned off after upgrade to SMEX 8.0.
 
Users will not be able to synchronize their e-mails through ActiveSync until these mails are accessed by mail client or scanned by a background scanning.
 

To resolve the issue, please do the following:
Step 1: Click on Start > Run and then type regedit
Step 2: Remove "VirusScanProactiveScanning" the key under each
"HKLM\SYSTEM\CurrentControlSet\Services\MSExchangeIS\FSSDAM\PrivateorPublic-
\"
 
Here's the exact location of the keys based on the registry logs you've
given:
 
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\me>\Pr
ivate-3484c833-f074-4793-97a0-0bbbcdbb7c75]
 
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\me>\Pu
blic-a785d57d-8a08-44ce-86c4-04bfea4691e5]
 
Step 3: Restart SMEX_Master service.
Step 4: (Optional) Perform a Manual Scan when mail traffic is low.

Good luck!

-- Bastian