Hi All,
Performed the cutover migration from OnPrem Exchange to Office 365 last weekend. While the migration itself went flawlessly, we are now starting to see performance issues with our internal Outlook clients 10 days after the migration.
We have a handful of 2007 clients left, all others are 2010. But the issue appears on both versions. It's not across the board, and it only appears to be select users that have the issue.
What we see is that, every so often, during normal operation, simply trying to select an email (new or otherwise), or open a calendar, results in Outlook freezing for between 20-60 seconds (shows Not Responding in the top window bar) before coming back to life.
I have checked the connection to the Office 365 servers on most of the affected clients, as per this link: