I am having an issue with Exchange 2010. Email are slow to populate in the inbox or users are receiving undeliverable messages to people they have emailed successfully before. I am receiving emails on my smart phone faster than my inbox. I am sometimes using the "Update Folder" on the Send/Receive tab and pulling in the new emails that I already got on my phone.
Exchange 2010 is running on a Server 2008 R2 Enterprise box.