Using cached mode. Random messages appear to "send," but actually get stuck in Outbox.

We are using Microsoft Exchange 2003 sp2 (front end server and mail server) with our Clients running Outlook 2003 in Cache mode. Some users are having the most bizarre random problem.

From their desktops, users will either reply to an e-mail or create a e-mail from scratch and click send. While the users believe the e-mail went to it's destination, the message does not show up in their sent items, and is not stuck in the Outbox. When I get a call about the issue, I can connect to Outlook Web Access, and there will be a handful of e-mails in their Outbox (which does not show up in cache mode), and some of which are months old. If I connect directly to their mailbox not using cache mode, the same handful of messages will be in their Outbox, and then they will send. These users don't even use OWA, so I know that isn't a variable.

Now I have users who need to reply to a handful of people as to why an e-mail they thought went out 2 months ago went out 5 minutes ago!

If anyone has any thoughts as to why this happened, or how I would be able to tell what other mailboxes are affected, or how to stop this from occuring again, it would be greatly appreciate!!!
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gupnitConnect With a Mentor Commented:
As  aproactive approach:
  • Make sure Outlook is all patched up to latest SPs
  • Make sure all Add-ins in Outlook are test and approved by you
  • Make sure AV is configured as per recommendations
  • Make sure that Firewall allows communication RPC
  • Make sure that OST is excluded from AV scan, that corrupts it very often
  • Make sure that you train the user to make sure that before he is leaving office or shutting down Outlook he checks his Outbox :-)
  • Send/ Receive Schedule is setup properly in Cached Mode
This should help you
Nitin Gupta (gupnit)
Have you tried to re-create any of the users profiles in Outlook?
Easiest way is to create a separate Profile from Control Panel > Mail
Set up the user account and check if the same issue occurs with the user(s) in question.

What are your results?
Over the years there have been many issues reported that cause this:
  • Corrupt Outlook Profiles
  • Firewall blocking it.
  • Junk Email Rules
  • Mesages too large
  • Make sure outlook latest SP has been applied (that corrects most such issues)
  • Some Add-ins (plugins) in Outlook
Also look at;en-us;195922
Making Bulk Changes to Active Directory

Watch this video to see how easy it is to make mass changes to Active Directory from an external text file without using complicated scripts.

As gupnit says and look also at the antivirus
JDF08Author Commented:
When I encounter this issue, I do recreate the users ost so a fresh copy of their mailbox is downloaded. However, I am still struggling to figure out how I know if a user is affected. Is it one of those issues where I have to "wait and see" or is there anything I can do to take a more proactive approach?
JDF08Author Commented:
Thank you for your helpful suggestions. We recently did change anti-virus vendors, and did NOT exclude the OST from the AV scan, so this would make sence as a source of our issues. Thanks again.
Glad to help
Nitin Gupta (gupnit)
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