I'm getting reports from multiple users that emails that are being sent to them are not showing up in their Outlook client for hours or even days later.
When I looked at one specific message, I could see that it was received by our Barracuda Spam Firewall on May 17th at 20:12. The message header also shows May 17th around the same time.
Next, I went to the Exchange toolbox and ran the message tracking utility. It also shows the EventID's for RECEIVE, EXPAND, TRANSFER and DELIVER were all on May 17th around the same time, shortly after the Barracuda received the message from our ISP.
The header and message tracking tells me that we're not having an email receipt problem, and mail is flowing properly into our system. But, the user said it just showed up in their Outlook 2007 client the morning of May 19th, almost 2 days later! This user was in the office on May 18th and using Outlook all day, but swears the message was not in her inbox until the 19th. Other users are reporting similar scenarios.
This is only happening on a few messages, not all messages to these users. And it's not just one user having this issue, so I don't think it's a problem with a specific computer or client install. As a result, I did not create new profiles for these users or reinstall Outlook.
Outlook 2007 clients are all running in cached mode (bottom right status bar says "Connected to Microsoft Exchange").