Everyone is using Outlook 2010, with a mixture of XP Pro and Win 7 Pro. Some users emails are delivered to their inbox with a 20 to forty minute delay. I checked the email headers using MX Toolbox and found the emails seems to be sitting on the server. I don’t see anything stuck in the queues.
All clients are using cached exchange mode. And the same thing happens with OWA and their iPhones. No one is using POP or IMAP.
I am not that familiar with Exchange 2010. Any help would be greatly appreciated.